Right after thoracic surgeon Dr. Xia is called back to treat an emergency patient, an unknown virus outbreak forces the hospital to go into lockdown, trapping Xia, along with hundreds of healthcare providers, patients, and their families. To find out the origin of the virus and stop it from spreading, Xia partners with tabloid journalist Jin. Registered nurse An and intern Li are also trapped in the hospital and despite the grave danger, they prioritize the patients and make unthinkable choices. Will they survive this epidemic?