Answer:
Bruno and Shmuel die at the end of The Boy in the Striped Pajamas when Bruno sneaks into the concentration camp to visit Shmuel, and they are sent to a gas chamber by Nazi soldiers. They are tricked into going into the gas chamber by being told that they are going to be taking a shower.
Step-by-step explanation:
After Bruno disappears, his father, the Commandant of Out-With (Auschwitz), commands his men to search for him, but they cannot find him.