We are first introduced to Colin in the prologue of The Running Grave, in which we see letters between him and his son Will, who has joined the Universal Humanitarian Church and is living at their main indoctrination centre, Chapman Farm, in Norfolk. We also see emails written between Colin and ex-UHC member Kevin Pirbright.

Sir Colin Edensor is Strike and Robin’s main client in the novel. He is the husband of Lady Sally Edensor, who died on New Year’s Day 2016, and the father of James, Edward and William. 

Colin was born in Manchester to a working-class family. His work in civil service got him knighthood, and he is a patron of several charities concerned with child welfare and education. 

Before approaching Strike and Robin, Colin and his wife, Sally, hire Strike and Robin’s private detective rival Mitch Patterson of Patterson Inc. Colin drops the agency after they botch the job – they used the same person who kept watch on Chapman Farm to approach a UHC member at Rupert Court, which was noticed by the church members. 

Colin establishes a relationship with ex-UHC member Kevin Pirbright. They mainly communicate over email and have the mutual desire to take down the church. Colin helps finance Kevin’s legal fees and shows support for the book he is writing about his experience in the church. 

Kevin is later shot dead in his home, which Colin initially believes was the work of the UHC, but later dismisses the idea.

Strike and Robin first meet Colin and his eldest sons James and Edward in the Reform Club on Pall Mall. Sir Colin tells the detectives that he decided to approach the agency after being recommended to them by the Chiswell family. Colin expresses his doubt about the likelihood of rescuing Will from the UHC, but nevertheless lays out the situation to the two detectives, who decide to take the case on, stating they don’t believe the case is entirely hopeless.

While Robin is undercover at Chapman Farm, it’s expected that she give a donation to the UHC. She writes a secret letter to Strike, who passes on the information to Sir Colin, who agrees to provide £1,000 for Robin/Rowena to donate to the church. 

Shortly after Robin escapes Chapman Farm and Will has turned up at the agency’s office, Strike meets with Colin for a lunch meeting at Rules restaurant for an update about the case. Strike tells Colin that it would be unwise to try and contact Will at this time.