From Thriller Picture Library #359, April 1961.
WWII is finally over. John Steel's job with Military Intelligence is over. He takes up the profession of private investigator and is soon asked to help recover a valuable book just stolen from a library. This in turn will lead to a case searching for a missing rich heir named John Pierce.
Note: this is a bizarre matter where the hero is a dark haired man named Dick Martin. He is identified as such several times so there is no mistake. Then on the 9th page, he is called John Steel! He will stay Steel throughout the rest of the story, including meeting up again with a woman who knew him as Martin in the tale's beginning.