People are collapsing in San Francisco with symptoms that suggest a whole range of pollution poisoning. As the Planeteers follow clues to solve this mystery, Ma-Ti (who is reading 1940s detective novels) keeps imagining himself as a private eye in black-and-white sequences. Ma-Ti proves a poor sleuth at first, but eventually he tracks down Verminous Skumm who is serving seafood tainted by storm drain runoff in his restaurant, The Sinking Ship.