Adrienne and Jack are happily married - but strange things happen that make Adrienne suspect that her husband is having an affair. After he is killed in a car crash, however, Adrienne discovers something even worse about Jack's past.
Adrienne (Hawn), a career woman of tactfully indeterminate age, meets cute Jack (Heard), a charming museum curator; five years later they have a happy marriage, an adorable child and a lovely home. But cracks start to show: a colleague is murdered with a polythene bag, one of the museum exhibits turns out to be fake, Jack is seen in New York when he should be in Boston, a tell-tale complementary hotel sweet shows up in one of Jack's suits, and the plausible excuses start running out.
Then, the big bombshell drops: Jack is killed in one of those every-inch-of-his-body-is-burned-and-we-had-to-identify-him-by-his-personal-effects car crashes that only ever happen in thrillers, and it turns out that Jack wasn't actually Jack at all, but Frank. Digging into her husband's real past, Adrienne finds out that - horror of horrors - she was married to someone from the working classes who borrowed the identity of a childhood friend. As she puzzles it out, a mysterious figure is seen loitering in the background, and it develops that the ambiguously dead man's schemes were even stranger than they seem.
Having more or less exhausted the possibilities of ditzy dizziness, Goldie Hawn here takes the route taken by many an earlier screen queen - Ingrid Bergman in Gaslight, Joan Crawford in Sudden Fear, Doris Day in Midnight Lace, even Julia Roberts in Sleeping With the Enemy - by stepping up the acting prowess by tackling the role of a powerful woman reduced to throat -clutching hysteria when the suave scoundrel she has married turns out to have murder on his mind. While Hawn strictly plays out the stock transition from gushy to puzzled to terrified, John Heard, borrowing a few Horror Husband licks from Terry O'Quinn's Stepfather, is a persuasive villain, effectively charming at the outset and nicely nasty when it comes for the Instant Divorce.
Director Damian Harris, the fumblefingers who made The Rachel Papers, pushes the right style buttons, with coolly menacing interiors and crashing orchestral climaxes, but can't quite pull off those Halloween-style short, sharp shocks that punctuate the rising tension.
It's not one of the best thrillers you'll ever see, but if you're in the mood for melodrama and can watch Goldie Hawn without feeling nauseated, this isn't so bad.