Four Found Dead is a YA thriller/horror novel. I bought my copy new.
Review:
The mall movie theater is one of the last places that held on after most of the businesses in the Riverview Fashionplace shopping mall closed. It's finally closing, however, and seven employees and one manager are there on its final night, cleaning and locking everything up.
Clayton, the manager, has always been disliked by his employees, but this evening in particular he's jumpy and angry. Then Jo notices that he has a gun on him, and she's instantly terrified - when she was 9, she witnessed her dad get killed in a gas station robbery.
As the situation in the theater rapidly devolves, one of the employees ends up dead and the rest of them find themselves trapped, locked inside with Clayton (who has the keys, and who took their phones at the beginning of their shifts because no one is supposed to be using their cellphones while working). So begins as tense game of cat-and-mouse as the group tries to figure out how to get to safety.