The Toxins Case: The Adventures of Constable Smith continues the story of Capella Smith from Grant Ross's previous book Read the Small Print. Having left her flesh and blood body on Earth, Capella is now in spirit form and has adopted a new spirit body. She has teamed up with Angelina Skyward, the Chief Detective Inspector of the Interstellar Police (ISP), to pursue criminals throughout the Milky Way. Their main challenge is the Interstellar Mafia (ISM), who plan to steal dangerous toxins and viruses for interplanetary blackmail. Their goal is to coerce other planets into surrendering valuable resources, including rare metals. Capella and Angelina quickly find themselves on the trail of the ISM, racing to stop their quarry's threatening scheme.