The Fourth Door by Paul Halter

Henry has had the gift since he was a child. He could perform spectacular magic tricks and bedazzle his audience with his skills as an acrobat and a conjurer. Henry lived with his father and mother, in a little village outside Oxford. Tragedy struck and Henry's mother was killed in an accident. Henry's father, Arthur, turned to a medium for solace.

The medium called Alice Latimer lives with her husband in a haunted house close to Henry's. One day Arthur is badly attacked, and left to die. His son goes missing and is blamed for the attempt on his father's life. Henry's best friend and the Latimers claim to see him at the same time at two different railway stations, but how can one man be at two places at the same time, is someone mistaken or another clever trick by Henry.

A few years later Alice Latimer, wants to do a seance and drive out the malevolent spirit from the haunted house, her husband, Patrick Latimer, offers to lock himself up in the haunted room and face the wrath of the enigmatic spirit. In front of witnesses the room is locked and sealed from outside, there is no way to either get in or out, a classic locked room, and where there is a locked room, murder can't be far behind. Poor Patrick is found murdered, but on careful scrutiny it is determined that the murdered man is not really Patrick. As more and more mysteries keep piling, the dead bodies also start piling up.

Paul Halter has been crowned the king of locked room mysteries and a successor to John Dickosn Carr, but does such an opulent title really suit him and his work?