I saw
The Atomic Man on TV many years ago. At the time I was surprised to recognize the story. It was the same as
The Isotope Man, a novel by English author Charles Eric Maine. I had always assumed the movie was adapted from the novel, but Wikipedia's entry on Maine (real name David McIlwain) says the movie came first.
Timeslip was its original title;
The Atomic Man is apparently its American release title.
The movie is a nice little espionage adventure with science-fiction trappings, nothing terrific but interesting and well-made. The story concerns a scientist who is found near death after being shot and thrown into a river. He dies on the operating table for a few seconds but is resurrected. When the man recovers he seems to have lost his mind. The lead characters try to work out what's wrong with him and why he was shot. If you want to see the movie, don't read any of the IMDB reviews or the very long (and very boring) synopsis. They all give away the clever gimmick explaining the scientist's infirmity.
The Atomic Man is in the public domain and it's available at
archive.org:https://archive.org/details/The_Atomic_Man_1955
