Due to sudden deteriorating weather conditions, visibility on the Airport Bridge is severely impaired, leaving people stranded and at risk of the bridge collapsing due to a series of chain collisions and explosions. Amidst the chaos, the canine subjects “Echo” from the military experiment “Project Silence,” who were being transported in secret, break free, and all human survivors become targets of relentless attacks. Various individuals find themselves stranded on the Airport Bridge for different reasons — a government official from the presidential office (LEE Sun Kyun) who was seeing off his daughter (KIM Su An) at the airport; a tow truck driver (JU Ji Hoon) who was on his way to a multi-collision scene; an elderly couple (MOON Sung Geun, YE Su Jeong) who were returning from a trip abroad; sisters (PARK Hee Von, PARK Ju Hyun) who missed their flights, and Dr. Yang (Kim Hie Won), the researcher responsible for Project Silence — and a desperate struggle begins for them to escape to safety.