It is a hot day at the Lakeside beach, and Inspector Brackenridge is relaxing in a deckchair with some beer. As he reaches for the next one, he believes he sees something strange on the lake, something like a monster. Suddenly... there is a scream. There is a woman's body on the beach. She is Katie Buchanan, who is a contestant in the Miss Purity competition, whose winner will be the new face of Alexander soap. At first sight, it seems that she has drowned, but a closer look reveals what appears to be a large animal bite. Miss Buchanan's body was found by her friend, Elaine Lawson, who is also an entrant in the miss Purity competition. Mr. Mason Alexander, the owner of the soap company, and the promoter of the competition, is also at the beach, trying to find people willing to watch the beauty pageant.
When Murdoch interviews Elaine Lawson she tells him that Katie had recently had an argument with another competitor called Marie Nicholson. The argument was over Katie's former boyfriend James Bennett, who had left her for Marie. Marie claims that this was because Katie was shamelessly flirting with one of the judges of the competition which she would do anything to win. This judge turns out to be Leslie Garland, Dr. Ogden's brother-in-law. Meanwhile, Constable Crabtree can only find one witness to corroborate Inspector Brackenreid's story of the lake monster, Captain Squires, a retired Navy man who has the property next to the beach, and whom Crabtree believes is unreliable.
Meanwhile, back at the city morgue, Dr. Grace is being overrun with victims of the heatwave. She able to confirm that Miss Buchanan died from drowning, though she is unable to say for certain whether the bite was before or after she died. Detective Murdoch (who has by now also seen the monster) and Dr. Ogden work together from measurements taken at the morgue to reconstruct the jaws of the creature which inflicted the bite. Intrigued by the possibility of discovering a new species of dinosaur, the two decide to spend the night at the lakeside. They go out into the water and begin canoodling, but soon Dr Ogden is sure that something has touched her under the water. Murdoch investigates and discovers the body of a second woman; she too appears to have a large bite mark. It is Marie Nicholson.
Who is killing the women? Is there really a monster loose in Lake Ontario? Is the generous prize offered by Alexander Soap enough to tempt someone to kill? Will Murdoch achieve fame for the discovery of a new species? For once Constable George Crabtree seems the only one in the police station to be making sense. He may believe in zombies, revenants, sasquatches and every kind of alien from Venusians to Martians but he won't accept that there is a lake monster unless he sees it for himself. Perhaps at some point he will hold the key to the entire mystery.
This episode has a good mystery story, as well as some delightful humour. The only thing I didn't like about it was the look that passes between Dr Grace and Mr Garland: neither would Constable Crabtree have liked it if he hadn't been distracted by his plans for the Next Big Thing.
