A large cross is part of Det. Tracy Vetter's protective kit against dangerous vampires.
In Hearts of Darkness, Tracy and her partner, Det. Nick Knight, are assigned to protect Ellen Simmons, who is believed to be a potential witness to a murder, if she only regains her full memory of events. Tracy knows the victim was bitten by a vampire. She takes precautions—which she heaves along in a large bag that raises brows at the police station, where it is assumed she has packed clothes and toiletries. In fact, the bag is filled with wooden stakes and heads of garlic, on top of which Tracy has added a large cross, in the hope of repelling the murderous vampire should she come to silence Ellen.