Henry Matthew Deaver is a death row attorney with a complicated and unique history in the town of Castle Rock, Maine. His estranged adoptive mother is Ruth Deaver, and he has a son named Wendell. He is the main protagonist of the first season of Castle Rock.
Henry Matthew Deaver was adopted by Ruth and Matthew Deaver. As a child in 1991, Henry went missing for eleven days. His neighbor, Molly Strand, watched on the night he disappeared as he got into a car with Reverend Deaver. The entire town of Castle Rock, Maine tried to find him. During the search, his father was found, half-frozen and with a broken back. He died three days later. After eleven days, Sheriff Alan Pangborn found Henry standing in the middle of the frozen Castle Lake. Henry showed no signs of being affected by the bitter cold, and was holding a carved wooden figure. The townsfolk believed that Henry had merely run away from and was hiding out in a warm place, making him indirectly responsible for the death of his father.
Unknown to any of them, and possibly even forgotten by Henry himself, Henry had somehow been transported to an alternate Castle Rock. He found his "father", Reverend Matthew Deaver (who was still alive in this timeline) and explained everything that had happened to him, including that he had at last heard the Voice of God. Initially, Matthew was overjoyed that a sign had come to him from God but soon came to believe that he was an agent of the Devil, sent to him when he needed it the most. Matthew drugs Henry and keeps him prisoner in his basement. For the next twenty-seven years, Henry never ages. He is eventually found by the alternate version of Henry Deaver, the biological son of that timeline's Matthew and Ruth Deaver after Matthew commits suicide.
Henry is eventually taken to the woods by that Henry and Molly Strand after Molly touches him on the hand and sees flashes of the other timeline. Henry is able to travel back to his timeline, remerging only 11 days after leaving. Unknown to him, the alternate Henry Deaver also follows him.
The blame for the death of his father eventually drove Henry out of Castle Rock, and he moved to Texas. Henry became a lawyer specializing in death row cases. After his latest appeal for his client, Leanne fails, he is contacted by someone at Shawshank State Penitentiary regarding a mysterious prisoner who has said his name, possibly as a request for legal help. Intrigued, Henry heads home to Castle Rock.
Arriving home, Henry finds his mother in a state of confusion, and Alan Pangborn living with her. He finds that his father's grave has been moved and no-one told him. Henry suspects that Pangborn might be taking advantage of his mother due to her condition. Heading to Shawshank, he is met by Warden Theresa Porter who feigns ignorance about any prisoner requesting his assistance since he does not know the prisoner's name. She makes him sift through a binder of prisoner photos to find any client that he might recognize and wonders if the phone call that brought him there was a prank. Not recognizing anyone, Henry leaves the prison. On the way out, he recognizes the voice from the phone call as Zalewski orders prisoners around.
Henry learns about Warden Dale Lacy's suicide, and Pangborn tells him that he committed the act at the same place where Henry was found. Henry drives out to Castle Lake where he remembers it as it was in 1991, and has a vision of his younger self standing behind him. When he turns around, everything goes back to normal.
Henry begins investigating Warden Lacy and goes to his house to talk to his blind widow, Martha Lacy. He fudge the truth a little about why he is there and gets access to Warden Lacy's office, to try and find any information on the mysterious prisoner. Henry finds a lot of "phrase of the day" calendars quote the same bible verse: "Even at that hour of night, the jailer cared for them and washed their wounds. Then he and everyone in his household were immediately baptized." Martha receives a phone call and realizes that he is Henry Deaver; she was a member of his father's congregation and orders him out of the house. Before he leaves, Henry notices a large padlock on the basement door.
Heading to the church, Henry asks the new pastor about Lacy and finds out that he did not attend the church. He would drop Martha off and then go to the woods; the pastor believed that nature was his church. At The Mellow Tiger, Henry meets Jackie Torrance and they talk until she starts to inquire about his disappearance. Henry stops the conversation, but gets the bartender to slip a message to Dennis Zalewski who was drinking in the bar with other prison guards.
Henry heads home and finds Alan digging up a dead dog to prove to Ruth that it is still dead; her condition has led her to believe the dog was alive and rooting through the garbage. Later, Henry talks with Dennis and they conceive of a plan to get Henry access to the prisoner. He can no longer walk in the prison since he is known there, so Henry joins the pastor's "Prayer Partner" program to help administer to prison inmates. Once inside the prison grounds, Zalewski arranges for the prisoner to be outside so Henry can see him through the fence. Henry tells the prisoner he will be his lawyer if he wants, and snaps pictures of him to prove his existence.