The Case of the Cannabis Cat begins with the Frayne family at the dinner table discussing the legalities of arresting a person. Tommy knows the Miranda warning but his Dad points out that the laws are different in Canada. The next day, a box is delivered to the Frayne home addressed to Tommy. When he opens it, he finds a little cat with a small barrel tied to a ribbon around its neck. He and his little sister are delighted with it but things turn awry when Constable Bidwell turns up and accuses the Fraynes of possession of illegal drugs. Because everyone refuses to answer questions, before long the Fraynes and the rest of the Private Investigators Club are sitting in an interrogation room in the police station.Luckily, Mary, a.k.a. Brains, knows enough of the law to argue against the 14 year jail term that Constable Bidwell is threatening.The story provides a look at the laws relating to possession of illegal drugs and gives the young private detectives a good idea about the severe penalties for drug possession and trafficking.