That night, when Nemo woke to the sound of cries, Jack’s bed stood empty. Perfectly made. “Dexter” had fallen asleep early, while Jack was still watching TV, and apparently Jack had never come to bed. And then the cries quieted without fading away altogether, and Dexter lay shivering under the covers despite the warmth of the summer night. A few minutes later, Jack crept into the room, tears streaking his face and a bruise blooming on his cheek. He wore no shirt and clutched a pair of torn pajama pants around his waist. Afraid, Dexter pretended to sleep as the boy he wanted for a brother sobbed quietly in the bed three feet away.

Two nights later Dexter awoke when only the moon lit the room and saw Jack’s bed empty again. This time, he would not be a coward, he told himself, but he made it no farther than the door of Mr. Gerrard’s bedroom—after that night he would never call him “Dad” again. The door stood slightly ajar and Dexter could see exactly what was happening on the bed, what Mr. Gerrard was doing to Jack. Though he did not have the words to describe or explain what he saw, the look on Jack’s face told him all he needed to know. And then Jack saw him and flashed a warning with his eyes. Jack, the ten-year-old, was trying to protect fifteen-year-old Dexter. And Dexter knew that was wrong, but he crept back to his room and lay awake the rest of the night. Jack did not return.

Mrs. Gerrard was visiting her sister in Ohio and when Mr. Gerrard announced she would be staying another week, Dexter made up his mind. Jack would never have to warn him again. He spent the day preparing. While Mr. Gerrard mowed the lawn and Jack watched TV, he gathered what he needed, stowing much of it in a backpack under his bed. He rehearsed every move in his mind over and over, making Gerrard react differently each time and adjusting his plans accordingly. It became a puzzle, almost a game, and Dexter relished the challenge. The motive, strong as it was, began to take a back seat to the planning.