In the bustling neo-Seoul of 2024, a chance encounter between Min Gae-in, a curious history student, and a frantic alien named Guardian sparks a time-jumping odyssey. Guardian, on the run with a fragment of the legendary Divine Blade, reveals a hidden war between humans and a malevolent alien force.
Meanwhile, in the war-torn future of 1380, the stoic swordsman Guard (played by Kim Woo-bin) searches for the remaining blade fragments. He encounters Ean (Ryu Jun-yeol), a Taoist shaman with the power to manipulate time. Together, they must forge an unlikely alliance with the past’s most skilled warriors, the ferocious Inquisitors led by the enigmatic Jaha (Kim Tae-ri).
Gae-in, armed with Guardian’s cryptic messages, stumbles upon a hidden chamber beneath the city. There, she meets the brilliant but jaded scientist Lee Ahn, the last of a lineage tasked with safeguarding the time gates. With 48 hours until a catastrophic alien device detonates, Ahn and Gae-in must decipher ancient texts and activate the time gate, propelling them into the future.
Thrown into the future’s chaos, Gae-in and Ahn reunite with Guard and Ean. Together, they face off against The Architect, the cunning alien mastermind wielding the complete Divine Blade, capable of warping time itself. A thrilling battle ensues, forcing them to combine their unique skills: Guard’s swordsmanship, Ean’s time magic, Ahn’s scientific ingenuity, and Gae-in’s historical knowledge.