tonight on "nightline," isaac's wrath. whole neighborhoods are under water, as this monster storm wreaks havoc on the gulf coast, exactly seven years after katrina. people are being rescued from their roofs once again. and as the rains continue to come, we're on the ground with the latest. tea time. a hotly anticipated night at the republican national convention as young gun vice presidential nominee paul ryan ignites the crowd and takes the tea party message national. and, conspirator in chief? it has been called unsubstantiated, dangerous, even crazy. and it is a giant box office success. meet the director who claims that he has proof that president obama has a secret, un-american agenda. >> announcer: from the global resources of abc news, with cynthia mcfadden in new york

city, bill weir in new orleans, louisiana, and terry moran in tampa, florida, this is "nightline," august 29th, 2012. >> good evening, i am bill weir. and much to the relief of everybody here, isaac is finally leaving town. but not without leaving new orleans very wet, battered and dark. hundreds of thousands of people will head into the holiday weekend without power. and here is the satellite map tonight, as isaac slowly churns north after more than 24 hours of just driving rain. still some powerful squalls on the tail end of this departure. and here's some fresh pictures from one of the most desperate places in isaac's wake. la plasse, louisiana, where water blown out of lake pontchartrain led to the evacuation of hundreds of families by bus, by boat. this follows also a day of rooftop rescues in the southern reaches of this area. much smaller than katrina, but still, an eerie example of

history repeating itself. in this part of louisiana, a lot of folks keep axes in their attics. exactly seven years after katrina, fred leslie is another reminder why. fred didn't have an axe and had to be cut out, plucked off his roof in plaquemines parish today. a harrowing experience for the 70-year-old and his beloved dogs. of course, in hindsight, it would have been a lot easier for fred to just leave when the evacuation order came down earlier in the week. but for storm-hardened lifers down here and older folks fond of home, it's hard to get too motivated about a category 1 like isaac. even when the president of the nation -- >> now is not the time to tempt fate. >> reporter: -- and the parish is urging you to go. >> we need you to move quickly and orderly and safely. >> reporter: and residents of the crescent city has 14 billion reasons to ride it out. that's how much tax money was spent shoring up the levees that so famously failed, leaving the

rooftop rescue a sad hallmark of this proud city. this is a little sample of what they got for those $14 billion. brand, spanking-new, mighty fortresses against the surging storm waters. and you can see, these federal levees are doing their jobs. but just down the mississippi, are old earthen levees only about eight feet high, which were no match even for this category 1 storm. sometime in the night, the surging water either topped or breached the old levees. and the rural suburb of braithwaite woke up with the realization that their homes were drowning, and fast. >> we had it break through the ceiling and come through the attic. and they took us out of the attic into a boat. it's very bad down there. very bad. >> i lived in braithwaite for 53 years and this is my first time seeing something like this. this ain't never, ever happened to us. this is a shame. >> reporter: some were rescued

by game wardens. others relying on the kindness of strangers, like jesse schafer, the third and the fourth. after watching 12 feet of rising water swallow their home in less than an hour, the father-son samaritans jumped in their fishing boats in the predawn dark and went hunting for the helpless. each says he saved around 60 people and dozens of pets. but it's the cries of the children they'll remember most. >> three kids we saw screaming on top of that roof, screaming their lungs out. so we wouldn't miss them, you know? >> reporter: when they came across ten people on one roof, the younger schafer gave up his seat on his own boat to make room for the old and sick. and had to wait to be rescued himself. >> when i was sitting on the roof for an hour today to give someone my spot on the boat, i was like, i'll sit here in a hurricane, on a roof in hurricane winds, risking my life for someone else.

>> we rescued a lot of people, saw a lot of things that you never thought you'd see. sorry. >> reporter: and it will be awhile before plaquemines is dry again. the whole gulf coast, for that matter. isaac may not have brought the blockbuster winds, but he brought way too much water to a region already saturated by a wet month. >> look at this. >> reporter: and extreme weather team member ginger zee is getting a first-hand glimpse across the border in mississippi. >> reporter: the rain here is absolutely relentless. you can see a mailbox there almost covered already. this is still the beginning of the rain. this will go on for days. that's why up to 20 inches can be found across the gulf of mexico. >> not sure we're going to be able to get through this part. >> reporter: and abc's ryan owens didn't need to step on the gas to follow the soggy eye of isaac, through louisiana to america's heartland.

>> the storm is moving so painfully slow that just by driving at normal speeds we've actually breached the eye wall. now we're into more of the difficult weather. you can see it's pouring outside. the car is blowing around a little bit, as we come closer to some of the hurricane-force winds. >> reporter: boy, what some of the folks in the drought-stricken midwest wouldn't give for some of this water, right? president obama did declare louisiana, mississippi, disaster areas tonight. that will open up some federal money for some of the folks down here. and 95% of the oil wells out in the gulf of mexico still shut down. gas has gone up nine cents in the past week, so, isaac may find its way into your wallet eventually that way. when we come back, my colleague terry moran will join us from tampa with the latest on paul ryan's big night at the republican convention there. and a reminder that in the morning, sam champion and his extreme weather team will have the latest on isaac's path on "good morning america." stay with us, everybody. [ female announcer ] they can be enlightening.

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>> announcer: "nightline" continues from tampa, florida, with terry moran. >> good evening from tampa, florida, i'm terry moran. day three of the republican national convention, where this hall was just buzzing tonight, because many, probably most of the delegates here, believe they saw and heard the future of their party and they hope the country. paul ryan, 42-year-old congressman from janesville, wisconsin, darling of the tea party conservatives and mitt romney's choice for vice president. well, he gave a speech here that just simply wowed the place. it may be mitt romney's convention, but tonight, it felt a lot like paul ryan's party.

he strode onto the big stage here tonight, a young man in a hurry. a gen-xor fired with a fierce, conservative passion. >> i accept the calling of my generation to give our children the america that was given to us with opportunity for the young and security for the old. and i know that we are ready. >> reporter: his young family watching in the hall, ryan delighted the crowd with a sharp and specific appeal to the young, to a lost economic generation. >> college graduates should not have to live out their 20s in their childhood bedrooms, staring up at faded obama posters and wondering when they can move out and get going with life. >> reporter: he rolled on, blasting president obama. >> these past four years, we have suffered no shortage of words in the white house. what is missing is leadership in the white house. >> reporter: and plunging into the debate over the future of medicare. >> the greatest threat to

medicare is obama care, and we are going to stop it. >> reporter: ryan's big moment up at that podium is, in many ways, a tea party triumph. since that movement spontaneously erupted in 2010, it has grown to an irresistible force in the republican party, sending establishment leaders scurrying for cover or scrambling to keep up. they drive the party's direction now, and in a lot of ways, they're having their own convention. a couple of blocks from the official proceedings, hundreds of true blue or true red conservatives streamed into a revival-style tent to lay the groundwork for an even more conservative republican future. and inside that tent, inside the revival, these grassroots activists are grooming a whole new crop of leaders to follow in paul ryan's wake. >> the stakes have never been higher. americans are uniting to turn our country around.

>> reporter: ted cruz shocked the political world last month when he won the republican nomination for u.s. senate in texas, crushing the hand-picked candidate of rick perry and the gop establishment. >> we are seeing a great awakening. >> reporter: you listen to him, and you know this is where the real energy, the future of the party is. >> i think the future are the people. i mean, what we have seen, the pattern that played out in 2010 and 2012 has been that grassroots matters. has been that elections are decided by the people on the ground. not by those in power, clinging to power. ♪ >> reporter: this is how political movements happen. and whatever you might think about tea party conservatives, they are remaking the republican party, the old-fashioned way. do you think this is a movement that fizzles or is it the future? >> look, i think it is

absolutely the future. you look at the beginning of 2012, a lot of media outlets wrote the story that the tea party is dead and i think they missed what had happened. in 2010, the tea party had a lot of protests, blazing hot sun. in 2011 and 2012, the tea party went to work. they rolled up their sleeves, they got involved in the party, they got involved in campaigns, they started block-walking, phone-banking. >> reporter: so, tonight, in the big hall, the future was happening. but for a moment, it was a voice from the recent past that held the crowd spellbound. >> i can remember, as if it were yesterday, when my young assistant came into my office at the white house to say that a plane had hit the world trade center. >> reporter: condoleezza rice stirred the delegates with her tale of american exceptionalism. >> a little girl grows up in jim crow birmingham, the segregated city of the south where her parents can't take her

to a movie theater or to a restaurant. but they have her absolutely convinced that even if she can't have a hamburger at the woolworth's lunch counter, that she can be president of the united states if she wanted to be, and she becomes the secretary of state. >> reporter: the crowd was primed for ryan and the future he represents. >> so, here is our pledge. we will not duck the tough issues. we will lead. we will not spend the next four years blaming others. we will take responsibility. we will not try to replace our founding principles, we will reapply our founding principles. we can do this. together, we can do this. >> reporter: so, still buzzing here, a little bit, even long after the big night for paul ryan. now, coming up just ahead, just in time for the buzz from the republican national convention, a big movie bashing president obama becomes a box

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now, the controversial conservative film, a surprise box office smash that makes the

shocking charge that president obama has a secret un-american agenda, as the filmmaker told abc's david wright. >> what is obama's real dream for america? >> reporter: "2016: obama's america" is already so successful -- >> the movie the white house doesn't want you to see and the story the media refuses to tell. >> reporter: that the author, dinesh d'souza, is fast becoming the michael moore of the right. are you surprised by the success of the film? >> i'm overwhelmed. this is my first venture into film territory. >> reporter: his controversial film makes the case that president obama has a secret agenda. >> obama has a dream. a dream from his father, that the fins of colonialism be set right and america be downsized. >> reporter: in the movie, d'souza stalks his way through obama's life story, as told in the president's best-selling memoir, "dreams of my father." >> my way of putting it was to

ask, what is obama's dream? >> reporter: but d'souza takes an entirely different spin. through hawaii and indonesia and kenya. he argues obama is motivated by an effort to please the radical father he barely knew. a man who has been dead for nearly 25 years. you take his personal narrative on which he built his political career and you turn it against him. >> i'm doing obama the credit of taking him seriously as a thinker and as someone who is a man of ideas. >> reporter: that's a little disingenuous, no? >> no, i say he's not getting results opposite to what he intends. he intends the results he's getting. >> reporter: he interviews obama's half brother, george, hospital whom the president has met only twice. years ago. >> you are his brother? has he been your keeper? >> go ask him. he's got other issues to deal with. >> reporter: he looks so much like obama. >> he looks a lot like obama, he talks like obama. he has some of obama's street smartness and native intelligence. >> reporter: but george obama turns out not to be a radical

lefty and d'souza suggests, for that reason, the president turned his back on him. do you really believe that barack obama wants to destroy america? >> no, i don't think he wants to destroy america but he wants to downsize america. i think he would like to see america have a smaller economy, use less energy, he'd like to see money redistributed away from america and toward the rest of the world. >> reporter: he spins out the theory by 2016 the u.s. economy will collapse and there will be a united states of islam, led by a nuclear-armed iran, and that obama wants it. >> if you seriously think it's a threat, you've got to do stuff that has the real prospect of stopping the mullahs from having a bomb. >> reporter: maybe he thinks we can't afford a war with iran right now. >> yes. >> reporter: which is a reasonable thing. >> it's a reasonable thing, and yet, for a country, america, which is, in a way, the sole protector of israel in the world, that would be a very

scary thing for a lot of jews to discover. >> reporter: the movie was produced by steven spielberg's producer from "jurassic park," "schindler's list." >> thought we were doing something righteous and right and i think we've been proven right there. >> reporter: people have voted with their box office tickets. >> they have. they have. >> change has come to america. >> reporter: this weekend, "2016" is expected to pass "an inconvenient truth" in box office revenues putting it right behind the most successful documentary of all-time. is that your hope, that it will be the "fahrenheit 9/11" of 2012? >> michael moore's a bit like the federal government. big, fat, out of control. i'm more like the private sector, lean and nimble. >> reporter: or, some would say, lean and mean. i'm affidavit wright for "nightline" in tampa. >> thanks for david wright. thank you for watching abc news. jimmy kimmel is up next. and we will see you here tomorrow.