A boy named Will has spent most of his childhood caring for his mother, who regularly experiences paranoia and confusion. He knows very little about his father, a man named John Parry who his mother says is an explorer. Will has never met him, but he envisions himself finding John and adventuring to exotic places with him.

In the months before the book’s opening scene, two men have come to Will’s house several times to ask about John, and have broken in to rummage through the house, obviously searching for something. Although Will’s mother has never told him who they are, he knows they are looking for a green writing case that contains letters, presumably from John.

One day, after his mother’s symptoms have steadily been getting worse, Will decides he needs to find his father. He takes his mother to his piano teacher Mrs. Cooper, who is confused but agrees to let her stay in a spare room. He returns home to find the writing case. Suddenly, the men come into the house and begin heading up the stairs. Will finds the case just in time and runs into the hall to confront the men. Startled, one of them stumbles on Will’s cat Moxie, falls down the stairs, and dies.