A lot can happen in 24 hours. A patient can die. A doctor can end up in quarantine. And all hell can break loose. Doctor Liam Alexander is still reeling from the loss of the patient he'd affectionately referred to as "Zero." When he wakes up, alone and abandoned in quarantine, he knows something has gone wrong. Upon further investigation of why he'd been abandoned, he discovers that quarantine had failed and the dead were rising. Liam teams up with Charlotte, a nurse who had failed to escape the hospital in the initial rising. Together, they must escape and find safety, or else succumb to the mystery illness they'd fought to contain.