Rowena Morrill is a SF and fantasy artist who has some really great vintage pulp covers to her credit. The above illustration is from the horror novel Isobel by Jane Parkhurst. Even by the high standard of vintage pulp covers, this one stands out as an outstanding example of compelling horror artwork, which has altogether vanished due to some incomprehensible reason. Can you feel the evocation of the dark? Does it give you the creeps?
In his blog Too much horror fiction, Will mentions that this was Morrill’s first cover art. Too good a debut even for someone too talented!
Here is the front cover of the paperback: