Leo and Bruno go to Grand Central Terminal, but are late to catch a train.
They have to run to the track. Bruno intentionally misses it, so Leo has to go alone.
He's taking the train to Isaac's house to try to get his book back.
On the train, he recalls the many times he fantasized about visiting his son.
He had always tried to keep up with things his son might be interested in, like baseball (the Dodgers) and rock and roll (The Beatles, Bob Dylan, the Rolling Stones).
When Isaac was a boy in school, Leo would stand across the street and watch him leave at the end of the day.
One time a letter arrived in the mail from Isaac's mother Alma. She wrote that she knows Leo watches her son, and that she waits for the day Isaac will ask for the truth. Also, she sees Leo in his eyes. Also, basically she's still in love with him—sigh.
The train arrives, and he takes a taxi to Isaac's house. He knocks and rings the bell, but no one answers. So he walks around back, picks the lock, and goes inside.
He puts on his son's shoes and his coat. He feels both very close to his son and very far away.
Leo walks around. He throws away some rotten food, reads a postcard taped to the window, and washes a dirty dish.
He continues looking for his book. He just wants proof that Isaac read it.