Doorway to Death — Helen Arvonen

Trudy Beecher and Kay Dee aren't really sisters, but they are so close that they lack only the name. So when Kay suddenly disappears, without a word or a trace, Trudy immediately tries to find out why. Kay's tracks lead to a lonely hunting lodge in the Canadian wilderness, where other girls have also mysteriously disappeared.

As Trudy's probing brinks her closer to the nature of the horror that dwells around her, she herself becomes the next victim. And finally, hunted down by the very menace she has been struggling to uncover, Trudy is forced to face the reality of the evil surrounding her -- alone.