Based on a character in John Dickson Carr’s The Department of Queer Complaints, Boris Karloff plays detective Colonel March. In this 26 episode television series we find Colonel March solve “unsolvable” mysteries. Being only 30 minutes long the mysteries don’t go very deep and in in the case of at least one episode, had a very “Scooby Doo” vibe to it. As of this writing it is available on TUBI
The role of Colonel March allowed Boris, then age 65, to go back to England to go into semi-retirement and visit old friends.