A body turns up in the morgue, causing Holmes and Watson to be drawn into the investigation of a serial killer who supposedly died in prison.
Tropes:
- Always Murder: Averted as the initial body found in the morgue was not a murder, but someone who was using drugs with embalming fluid and was startled by a robber. The fact the he fell onto a body getting a bite mark is what makes Holmes and Watson aware of the recent killings that involved biting.
- Jack the Ripoff: Holmes and Watson try to determine if Colville was innocent and the real killer has returned, or if he was guilty and the new murders were committed by a copycat. Not only Colville was guilty, but the copycat was his mother.
- Mama Bear: Ruth Colville committed two murders to exonerate her son.
- No Good Deed Goes Unpunished: Ruth Colville lured her victims by getting them to help her with groceries.
- Serial Killer: Both Aaron and Ruth Colville were budding serial killers who only lacked the count to qualify.
