steven stayner is plucked off the street and held captive for seven years. out, the monsters weren't gone. >> all this rage that's building up in cary. >> it's rile there. he's this vicious killer, but he's even more twisted than that. and they're about to find out just how twisted. >>> so as winter merges into spring, the entire valley just seems to come to life. everything turns green again. it's a completely different feeling. >> it's march, 1999, and this spring is different, because there is a palpable fear in yosemite park. >> a very mysterious story. three people have disappeared. >> the sunds were last seen near the yosemite valley. >> -- where the trio had been visiting. >> in february, carole sund, and her daughter, juli, and their teenage friend silvina pelosso had gone missing from the cedar lodge. >> i can't imagine how three people in a red car could disappear. >> this doesn't happen in the national parks. there was a sense of panic. >> there was nobody here. even the locals stopped coming in. >> you can't overstate the sense of fear there. ever