This study guide was created using the following version of this book: Stevenson, Benjamin. Everyone In My Family Has Killed Someone. Mariner Books, 2022.

Ern Cunningham is a self-published author of guides to help writers write mystery novels. Ern’s brother, Michael, comes to Ern for help after murdering Alan Holton. He needs help to dispose of Alan’s body, Ern ultimately testifies against Michael, sending Michael to prison.

At a Cunningham family reunion three years later, Ern is interacting with most of his family for the first time since Ern testified against Michael. After a body is discovered on the ski slope at the lodge where the Cunninghams are holding their reunion, Ern sets out to try and solve the murder. The body, known as Green Boots, is suspected to have been killed by a serial killer called Black Tongue. Black Tongue kills his victims by causing them to suffocate on ash.

When Michael arrives, newly out of prison, with Ern’s estranged wife Erin, Ern must put his feelings for Erin aside. Officer Crawford, an inexperienced local police officer, arrests Michael for Green Boots murder and detains Michael in the Drying Room of the resort. Michael identifies Ern as his lawyer so that Ern and Michael are able to speak freely. Michael tells Ern that while Michael was in prison, Michael uncovered information about their father Robert’s death when they were children. Michael also wants Ern to check out the evidence Michael has hidden in his truck.

Ern checks out Michael’s truck and finds an exhumed coffin with the body of the police officer Robert killed years earlier in it. Ern also sees that the body of a child was also buried with the officer. While in the truck, Ern feels the truck start to roll downhill. Unable to escape from the truck, Ern injured his hand when the coffin pins Ern against the wall and the truck ends up sinking in a frozen lake.

Ern is rescued from the lake and soon discovers that Michael has been killed by the Black Tongue killer. The Cunningham family rallies together as Ern tries to piece together a decades-old mystery of what happened the night Robert died. Ern realizes that Robert’s death and why Michael killed Alan are connected. As the family mourns Michael, Michael’s estranged wife Lucy goes missing.

With the help of Juliette, the manager of the resort, Ern and other family members go out to search for Lucy. The group ends up at a nearby resort where Ern meets Edgar and Siobhan McAuley, an older couple that Michael was dealing with before he died. Decades earlier, Edgar and Siobhan lost their daughter Rebecca, the child that was buried in the coffin with the police officer.

Back at the resort, Ern gathers the family together to walk through his theory about what happened years earlier and solve the Michael’s murder. Ern reveals that Officer Crawford is the long-thought-deceased brother of Ern and Michael’s. Ern discovers the proof of Rebecca’s murder which led to Robert’s death, and the conspiracy surrounding the Cunningham family for years.