Yes, that's a face on the book's cover and yes, it's in a jar. However, the woman depicted is probably NOT Eleanor Rigby.
I first became familiar with Bill (I knew him and was told to call him that) Johnstone through his myriad of oddball horror novels. He also wrote post-apocalyptic stuff, Westerns, military thrillers and worked in many other genres as well.
NIGHT MASK is one of his more unusual books because it combines a serial killer story with some other weirdness, including werewolves.
You never knew what you were going to get with a Bill Johnstone horror novel; therein lay the charm.
I hope they re-print all his horror novels so that I have a fighting chance to get those I missed.