The plot is set in motion when a man named Mr. Morehouse goes to a parcel office at a train station to collect two guinea pigs. He expects to pay twenty-five cents, the rate for sending domestic pets by rail, for each animal. Mike Flannery, who runs the parcel office, insists that the rate for sending domestic pets does not apply to guinea pigs. He believes that guinea pigs are a kind of pig and that Morehouse should pay sixty cents, the charge for transporting two pigs, for the animals. Morehouse refuses to pay the higher charge and complains to the railroad company. While Morehouse waits for the matter to be resolved, the guinea pigs are left in Flannery's care. The two guinea pigs soon have six children. After a few months, Flannery finds himself having to take care of thousands of the