Jack and Rowe board an airship to investigate the proposed illegal sale of a replica "mermaid’s foot", an Ishtar sacred object. The royal family is trying to remove these replicas from the market and Jack and Rowe suspect Professor Freud and his assistant Linda are the sellers. Jack and Rowe fake the death of their buyer, but Freud and Linda implement an elaborate plan to pretend the object was stolen from them. However, Jack and Rowe are not fooled and Linda, a professional bodyguard, attacks Rowe, but they are defeated and caught.