As American Horror Story: Hotel Season 5 Episode 8 begins, John runs after Wren, the girl who was known to have worked with the Ten Commandments killer. The girl is dead, and in that moment, John recognizes her as one of the girls from the coffins at the Hotel Cortez. 

Liz Taylor tries to manage her grief but John makes that difficult when he demands to see the Ten Commandments killer. Sally shows up and volunteers to take him to see the man he's been hunting. Liz gives them a gun and they go to room 64.

Sally begins telling John the story of James Patrick March's death and sends him to the armoire to look behind it. There he finds a chamber with evidence from the murders, evidence catalogued into police evidence. Slowly he begins to believe that he is the killer. He goes to his partner to confess to the murders.

The first time he stepped into the Hotel Cortez was 2010, despite his partner believing he only encountered the hotel for the first time three weeks prior. After drinking martinis in the bar, he was taken upstairs to meet The Countess and James Patrick March. They drink absinthe and March lures John into his murder club against John's knowledge. 

James and the Countess conspired to turn John into a killer. She helped him forget his time with James and then stole his son, pushing him into the darkest places of his heart. After Holden's absence, John began living two lives. One at home with Alex and one in the hotel with James. 

After his first kill, John tried to take his own life. James cut him down and reiterated the terms of his agreement with Sally. She will get to keep John, eventually, but for now James needs John to continue his work. 

Hahn doesn't believe his story, so John kills him, making him another trophy in the Ten Commandment murders. John takes the prize to the Hotel Cortez and tells James he plans to finish the tableau.