As memory serves, this was actually the PILOT for a series, where, presumably, each week Davis would get involved with somebody whose soul Davis was trying to acquire...!  (It was sort of a switch on that series idea that several folks have attempted, an angel on earth trying to help folk...)

I remember watching this back in 1973, with JACK KLUGMAN--at the height of his ODD COUPLE stardom!--playing the fella Davis was trying to purloin, with Adam West (!) as, I think, his chic but nasty boss, who was trying to sleep with his wife!

A quick Google check just showed me that this was executive produced by veteran comedy writers Arne Sultan (who was a story editor, and then executive producer on some seasons of GET SMART) and Earl Barret.  (The duo later produced TOO CLOSE FOR COMFORT.)  Intriguingly, the cast also included Madlyn Rhue and the great Gino Conforti!  As a kid, I LOVED Gino Conforti!

Best, Jim