Abby Black lives in Brooklyn, in the narrowest townhouse in the city. Abby is one of the first Blacks that Oskar visits, but, as it turns out, she holds the key to the mystery of the key: her husband, William Black (much farther down the alphabet) knows about the key and has been searching for it. She left a phone message for Oskar after he came to visit her, but he doesn’t hear it until eight months later. The message cuts off in the middle because Oskar’s Mom picked up the phone, which is how Mom figured out about the expedition.