Mr. Black knows about many things but not the key. When Oskar asks Mr. Black if he knew his dad, Mr. Black looks through his bibliographical index, where he distills every person he’s ever written or read about into one word. Mr. Black’s card for himself originally said “war” but now says “husband.” He has no card for “Thomas Schell.” Oskar wishes his dad had been someone great so that he’d be bibliographically significant. Mr. Black asks why that matters when most entries get summed up as war or money anyway. 

Mr. Black made his bed from a tree whose roots his wife tripped over. For most of their marriage, Mr. Black left his wife behind while he reported on wars. He later realized that what he wanted was to be with her. He cut down the tree as his last war. Mr. Black hasn’t left his house in twenty-three years. Oskar wishes he’d known Mr. Black was there so he could have visited him.

Oskar invites Mr. Black to help him investigate the key. Mr. Black turned off his hearing aids years ago and has been lip reading their entire conversation. Oskar asks if he can turn them back on, which he thinks would be beautiful and true. Mr. Black acquiesces. Birds fly past the window, and Mr. Black starts crying. He agrees to help Oskar.

When Oskar’s mom tucks him in that night, he tells her not to bury him when he dies. His mom promises he doesn’t need to worry about dying. Oskar counters that dad didn’t think he was going to die when he did. Mom asks why he wouldn’t want to be next to her and dad. He argues that dad’s coffin is empty, and his cells are all over New York. He brings the conversation back to the mausoleum, trying to make the request funny because if he makes his mom laugh, she won’t be mad.

He changes his mood in his journal from “desperate” to “mediocre.” He says he misses dad. His mom agrees, but Oskar doesn’t believe her. She asks if he thinks that her laughing means she doesn’t miss dad. Oskar updates his mood to “depressed.” He tries to make his mom promise not to fall in love. She says he reminds her of dad.

Oskar says if he could have chosen, he would have chosen her. Oskar’s mom leaves. Oskar updates his journal to “incredibly alone.”