When Cassie goes to retrieve water bottles from a convenience store a few weeks after the death of her father, she finds a wounded soldier sitting behind some shelves. Due to her experience with the soldiers who took Sammy and killed her father, she does not trust that this man is human—despite his injury and the fact he does not kill her the moment she walks into the store. When the soldier moves his hand and she sees an object hidden on his person, she shoots him without thinking. Cassie is afraid and does not want to die, but it turns out, the soldier simply had a crucifix.

The crucifix soldier becomes a motif representing the theme of Futility Of Action. If Cassie did not shoot the soldier, he might have shot her with his hidden object; however, she does shoot, and it turns out she killed him in cold blood. She could not have known whether or not he was dangerous. The crucifix soldier also becomes a motif of the lack of trust between characters during the fourth wave. It is near impossible for humans to know whether or not other humans are infected with Others. For this reason, they do not trust each other and often kill innocents out of fear.