Laura and Leigh Lockwood are fraternal twin sisters who are anything but alike. Leigh [Donna Mills] is beautiful, poised, confident, and has per pick of men for a date. Laura [Patty Duke] is a mousy, shy Plain Jane that most men hardly give a second glance at. Leigh has had her share of lovers, while Laura is starved for a love life.Enter Valerie Steffan. Not much more pretty than Laura, she is dark-haired, speaks with a German accent, and is very assertive and likes to pick up men at bars... many of who were previous lovers of Leigh's. On the night of a full moon, Valerie goes out in search of a man to spend the night with... but she tends not be successful in persuading them to come home with her for the night. As a result, the men tend not to be successful in waking up the next morning... because they are found dead in an alley with large, gaping puncture wounds in their chests... wounds that ooze with spider venom.Veteran police detective Mark Higbie [Tony Franciosa] begins investigating these murders. Asking around, he hears an explanation from a bar owner who doesn't believe what he, himself, saw... a black widow spider fully the size of a human being. Following the trail through Los Angeles, he finds there is an involvement with Leigh and Laura. Digging further, he learns that the Lockwoods's late parents were doing research on black widow spiders... and one of the children was bitten by a large number of them. Then he hears an old Indian legend about a woman with a red-hourglass mark on her abdomen-- just like a black widow spider has-- that in times of stress, turns into a giant spider and kills. Of course, bullets won't stop such a creature-- only fire will.The movie climaxes with the revelation that Valerie Steffan and Laura Lockwood are one and the same. Laura has a multiple-personality disorder; Valerie manifesting in response to Laura's feelings of social inadequacy compared to her sister. Laura and Valerie know of each other, but only Valerie knows how to use Laura's curse. When Valerie is given the brush-off by men she tries to pick up at bars-- most often men who have had relationships with Leigh-- she takes on spider form and kills them. Laura is tormented by her vague awareness that Valerie is killing these men... but she has only fragmented trace memories of how.Now Detective Higbie must find a way to stop Valerie and her monstrous power before she kills again... and Valerie is getting wise to the fact that the detective is on to her.
What are the names of the fraternal twin sisters?
Laura and Leigh Lockwood