Scooby-Doo and Shaggy must go into the underworld ruled by the Goblin King in order to stop a mortal named The Amazing Krudsky who wants power and is a threat to their pals, Fred, Velma and Daphne.

本片讲述了随着钻石的神秘失踪，伦敦警方组织了很多侦探去查找罪犯，汤姆和杰瑞就是一对组合。棘手的案件让这对猫鼠痛苦不堪，只能寻求世界上最棒的侦探的帮助，他就是夏洛克·福尔摩斯先生。