After receiving a strange (and unintentional) blackmail call, Conan elicits the help of Heiji Hattori to track down its intended recipient. However, once they find the victim they discover that the perpetrator has stolen his expensive and valuable jewel – a jewel that the mischievous Kaitou Kid desires for himself! Conan and Heiji must once more use their skills of deduction to unveil the identity of the villain and save the valuable prize.