Don't mess around with your teenaged sister-in-law! You'd think guys would've learned that lesson by now. Handsome Dr. Michael Walsh (McMahon) and his lovely wife, Helen (Storry), have a seemingly happy life with their daughter Brittany. Then Helen's sister Magenta (Atkins) comes to stay and she and Michael are soon exchanging more than eye contact. Naturally, all this leads to betrayal, lies, and even more problems.