In Pangu City, a lively metropolis where extraterrestrial and human civilizations intermix, numerous aliens live disguised as people, seamlessly fitting into daily life. These include alien inhabitants, tourists, and dangerous criminals. The elite "Interstellar Detective" force is assigned to pursue these malicious beings. The conceited detective Xiao Bei chases the intergalactic thief Lambda to Earth, where he gets help from a local girl named Xiao Yi. While posing as a human boy, Xiao Bei creates many comical misunderstandings, but by teaming up with Xiao Yi, they capture countless villainous aliens. Together, they defeat the mighty Thunder Lizards, the insane Bat Doctor, and the stubborn Tree Shepherd—ensuring that no alien offender can conceal themselves on Earth. Using advanced alien gadgets and endless ingenuity, they connect clues about Lambda and finally stop the alien syndicate's plan to drain Earth's life force, bringing Lambda to justice.
