Lorentz’s YA debut cogently explores the impact of an emergency situation on multiple characters in a finite space. An ordinary day at the mall turns deadly after the discovery of a biological bomb in the air ducts prompts an immediate lockdown, trapping thousands of shoppers inside. With information scarce and security on alert, everyone approaches the situation differently. Restaurant worker Marco tries to do his job, senator’s daughter Lexi attempts to figure out the truth, quirky Shay takes care of her ailing grandmother, and athletic Ryan joins others in an effort to escape. As their paths cross and stories overlap, these four teens find friends and romance, even as society breaks down around them and a fatal disease claims numerous victims. This tense trilogy opener takes its time establishing the memorably diverse and sympathetic characters, while foreshadowing and vivid staging (stores in the mall take on special significance under the circumstances) build a sense of claustrophobia and desperation. Very little is resolved before the inevitable cliffhanger, but readers will eagerly await the next installment. Ages 12–up. Agent: Faye Bender, Faye Bender Literary Agency. (May)