Brown, Fredric - Death Has Many Doors

Death Has Many Doors sees Hunter and Hunter's PI firm approached by a young girl with a weak heart. Sally Doerr believes she's being persecuted by Martians. They plan to kill her and she wants protection. Ed reluctantly volunteers to accompany her home. He spends the night on the couch, but in the morning Sally is dead. There's no evidence of violence, but he's sure something is wrong. Then Sally's sister Dorothy turns up. She also has a premonition of death. Ed takes her out of town, watches her like a hawk - and nearly loses his own life when she dies. The murderer is clear; but how was it done? A long investigation clears up all the possibilities but one; and the murderer is caught.

Jon Jermey

See also: http://moonlight-detective.blogspot.nl/2012/06/martians-go-home.html