Katherine Heigl, Ashton Kutcher, Catherine O’Hara, Tom Selleck, Casey Wilson, Kevin Sussman. Director: Robert Luketic.

HONESTY is the cornerstone of any healthy and long-lasting relationship but perhaps it is sometimes wiser to keep a secret than to share it with a loved one.

According to a survey of 3,000 women aged 18 to 65 conducted last year, they will typically share a secret within 48 hours of hearing the juicy morsel of gossip.

If Robert Luketic’s action-packed romantic comedy is to be believed — and it is an almighty stretch — men are capable of hiding everything from their nearest and dearest.

In the case of the film’s charming hero, he manages to meet, woo and marry the woman of his dreams without revealing a vital part of his genetic make-up.

His unsuspecting wife will definitely regret her wedding vows to love him ‘til death us do part.

Jen Kornfeldt (Heigl) doesn’t believe that she will ever fall in love again after her current boyfriend dumps her.

Consigned to life as a singleton, Jen reluctantly goes on holiday with her overly protective pilot father (Selleck) and boozy mother (O’Hara) to the French Riviera where she meets handsome consultant, Spencer Aimes (Kutcher).

Jen is instantly attracted to his washboard stomach and warm smile, and the couple enjoys a slightly drunken first date.

Three years later, Jen is married to Spencer and happily settled in a close-knit community with white picket fences and kooky neighbours.

Alas, Spencer has been keeping a tiny secret: he is an international spy and assassin, who retired from active duty but has now been marked for death.

When Jen is caught in the middle of a gunfight, she finally realises the full horror of her situation as sidekick to a trained killer.

”So what am I, Pussy Galore?” she shrieks.

”Not that I know of,” retorts Spencer ”So now you’re complaining about our sex life?!” counters Jen angrily, her rosy future shattered to smithereens.

Killers is an odd mishmash of genres, veering wildly from action to comedy and back again, sometimes in a single scene.

Kutcher and Heigl are far better than the screenplay, which reduces the former to shirtless eye candy and the latter to an unadventurous homemaker.

Spencer tries to justify his interest in Jen by telling his handler, “She’s normal and I feel normal when I’m with her. I like that.” If he says so.

On-screen chemistry simmers but never catches fire, extinguished almost entirely by the stunt-laden finale.

Selleck twitches his fine moustache as the patriarch with secrets of his own and O’Hara is broad comic relief as a lush whose idea of ‘hair of the dog’ is a quart jug of extra strong Bloody Mary.

With all of the explosions and sparks from ricocheting bullets, it’s a miracle she doesn’t go up in flames too.