Iain is the Chief of Police for the Waterbury Police Department, who attempts to use his resources to catch the Executioner. However, after kidnapping Ariel Peterson, he uses his status and power to keep Sarah and Cam from finding her.
He is the ninth of the Executioner's victims, representing the sin of lust— where he was knocked out and placed inside a crematorium furnace, burning him alive.
During the night of Ariel Peterson's disappearance, a few minutes after Trent McBride and June Henry left her by herself, an off-duty Iain pulled over intending on driving her home. But after Iain drove past the Peterson home, telling Ariel she should sober up first, they start talking which prompts Ariel to praise Iain for "being a hero." Iain ends up pulling over and raping Ariel.
In the years that followed, Iain imprisoned Ariel in a room-sized safe in his basement as a concubine. Further confining their four-year-old son Jake, with her.
Iain and Nancy have been married for an undisclosed number of years. She is aware of Iain's involvement in the Ariel Peterson disappearance, and does nothing to stop him. It's unknown if she supports them, but regardless, it's assumed that Nancy has no other involvement other than her awareness. It is hinted that for not having a child is the possible cause as to why their marriage is broken
On the night of Ariel's disappearance, Iain picked her up meaning to bring her home, but after feeling attracted to Ariel (because of her comments about his heroism) he raped and kidnapped her.
Not long after, Ariel and Iain have a son named Jake. Iain was prepared to kill both Ariel and Jake to keep his secret from coming out. But then let them go after being cornered by the police.
Iain and Marjorie had an unknown past together, presumably with romantic or sexual undertones. It's implied that she was at the very least, aware of Ariel's involvement with Iain— even offering to lie to the police for him. However, it became exceedingly obvious that Marjorie was more of a loose thread than an accomplice, since Iain killed her to cover his own tracks.