Two Transmigrators of the Great Qian

A SWAT officer and a scientist die in the apocalypse and wake up in Great Qian. They become sworn brothers and pacify unrest, until the scientist turns traitor and tries to usurp the throne. After the rebellion is put down, the traitor escapes with his past-life lover, while the SWAT officer marries the princess and becomes the King of Yunzhong.