Seoul, 2004. A group of bikers tears through the city streets, led by the teenage Han Ki-su, [Lee Min-ki], who is tearfully berated by his girlfriend Chun-shim, [Kang Ye-won], for scorning her. Watching the moment with a quiet ache is Kim Myung-sik, [Kim In-kwon], who is secretly attracted to Chun-shim. After a tense stretch of heavy traffic, Ki-su nails a flawless jump over the obstacle, earning a mix of awe and danger as the ride ends.
Six years later. Ki-su has become a bike messenger, weaving through Seoul’s busy lanes. He delivers a package to an office, and just after he leaves, the building erupts in a blast. Ki-su dismisses the thought that his delivery could be connected to the explosion, but the event casts a long shadow over him. Later, he’s asked to drive Ah-rom, the lead vocalist of OK Girls, to a televised stadium concert that she’s late for. To his surprise, the star singer is Chun-shim, still angry about how she was treated years before.
Ki-su offers her his helmet, unaware that it has been swapped for an identical one rigged with an explosive. A phone call then pulls him into a grim countdown: deliver three packages already stowed in his bike, each with a 30-minute limit. If the timers run out or if Chun-shim tries to remove the helmet, the device will explode.
On the police side, the investigation intensifies. The police, led by Detective Seo [Ko Chang-seok] and the NPCC team leader [Kim So-jin], study CCTV footage from the blast and begin to view Ki-su as the bomber. The pressure tightens as the pair of fugitives—Ki-su and Chun-shim—make their way toward the concert, all while the clock ticks and shadows of motive begin to surface.
Ki-su ultimately delivers Chun-shim to the stadium just in time, and she performs while wearing the dangerous helmet. With the countdown still active, the two of them hit the road again, crossing between Seoul and Incheon as they push to complete the dangerous deliveries. They move through a city that feels both familiar and perilous, all the while being pursued by law enforcement and trying to uncover who is truly behind the bombings and why this deadly chain of events has dragged them into the middle of it.
