curators working with billionaire thomas kaplan get down to work. a way of signing things, just with an "r," and when it was cleaned, there was an "r" there. >> case closed. >> what's so crazy about this story is that not one person in the united states recognized the significance of this remarkably unremarkable painting. an old master dealer came from the city, and sat in the front row.old master specialist comes and walks right past the rembrandt. >> yes. >> even after the painting's authenticated, we can only guess how it ended up in the landaus' new jersey home. >> would've come from europe at some point. i think the size had a lot to do with it being able to cross the atlantic. >> the landau brothers figure it's time to do a little sleuthing into the grandpa they barely knew. >> we learned that our grandfather phil liked on the weekends to drive from paterson into manhattan, and he would hang out at this auction house. >> really? >> they sold estate sales from people who had apartments in manhattan. and so, i think that grandpa liked the idea o