Picture this: Your marriage has crumbled, you’re barely coping, and your spouse already is happily engaged — meaning a stranger will be helping to raise your child. You’re jealous and pissed. Not a recipe for shiny happiness.

Here is the first trailer for Unforgettable, a thriller from producer and rookie director Denise Di Novi. Katherine Heigl plays Tessa, for whom the ugly scenario outlined above is a fact. Her ex (Geoff Stults) has taken up with Julia (Rosario Dawson), who is trying to settle into her new role as a wife and a stepmother to young Lilly (Isabella Rice). Julia believes she finally has met the man of her dreams, who can help her put her troubled past behind her. But Tessa’s jealousy soon takes a pathological turn until she will stop at nothing to turn Julia’s dream into her ultimate nightmare.

“There was a time when I thought we were on the road to getting back together,” Tessa confides over drinks with Julia. “Then,” she adds ominously, “he met you.”

Unforgettable marks a reunion for Heigl and Di Novi, who worked together on 2010’s Life as We Know It. Simon Kassianides, Whitney Cummings, Robert Wisdom and Cheryl Ladd co-star in the film written by Christina Hodson and David Leslie Johnson. Warner Bros opens it wide on April 21. Check out the trailer and tell us what you think.