Ok, Boris takes him to Amsterdam where he has set up a sort of heist to get the painting. They get it back but then are ambushed by two henchmen of one of the NYC art ganstas who get it off them, in the melee theo shoots and kills one of them.
Theo goes back to his hotel and Boris goes AWOL with Theo's passport.
Theo realises that he can't get out of holland without a passport, it is Xmas eve and the embassy is shutting. He contemplates suicide and starts writing notes to kitsey, Pippa, mrs Barbour and hobie.
Then he changed his mind (cabt remember why?) and decides to hand himself in, confessing to murder as well as the art theft.
Just then Boris reappears (on Xmas day) with a caseload of money. He explains he has contacted the art police and told them who has the goldfinch and while investigating the police find huge amounts of more stolen art. Boris had huge £££ sum in reward money which he gives to Theo, along with his passport.
Theo returns to NYC and explains all to hobie (hobie is cross with him for leaving Pippa an expensive necklace and confessing his love for her/ we find out later that Pippa loves him too but thinks they are both too damaged by the accident to be compatible).
Hobie reveals that Welty loved the goldfinch as he knew a replica of it as a child. Theo uses the reward money to travel the world buying back the antique forgeries he sold. His marriage to kitsey is sort of on hold but recognised by both of them as convenient....
Think that's it in terms of plot- there's a lot of philosophical musing on art, live etc at the end!
Hth!