With Phantom Stranger 12 (March/April 1971) Dr. Thirteen splits off to have his own back-up series in the book.
Neal Adams once again provides the cover for the Phantom Stranger tale, by Kanigher and Aparo. It's a decent enough outing, although very predictable. The story centres on a newly married couple. The man had been married once before, and his wealthy wife had died. She had made it a condition of her will that he bring her corpse (in the coffin) with him wherever he went.
This creeps out the new wife, and the guy is clearly haunted by the situation as well, sleep walking and imagining that he sees her. The Phantom Stranger's role in the story is fairly small, and actually fulfils much the same purpose as the dead wife, stalking the guy and bringing out his feelings of guilt.
It's no shocker to learn that he allowed his wife to die, refusing to bring her her medication. At the end the new wife convinces him to have the coffin taken away, but the guy gets run down and killed by the car that comes to do this.
Jack Oleck and Tony DeZuniga give Dr. Thirteen his first solo story since the late 40s. Marie Thirteen has a very small role in this one, as Terry deals with superstitious townspeople who think a ghostly monk is killing people using sound.
Dr. Thirteen examines the clock tower, which is the apparent source of the deadly emanations, and the graveyard where the mysterious monk appears. He unmasks the man as the old town doctor, who was using a sonic weapon to kill the people who had brought in a new, younger doctor to replace him.