Michael Courtland's (Cliff Robertson's) second wife (Genevieve Bujold) is actually his daughter, whom he thought had been killed along with his first wife. (Eeeewwww!)
Thanks, ucladavy and Jeff S!

(Links open in new window)
Read more about this film at The Internet Movie Database.

Buy it on DVD at Amazon.com.

Buy this poster at moviegoods.com