A largely unpleasant payback thriller, “In the Blood” is built around the bone-crunching skills of mixed-martial-arts fighter-turned-actress Gina Carano, the star of Steven Soderbergh’s 2011 action drama “Haywire.”

As with “Haywire,” “In the Blood” finds Carano’s tough heroine, Ava, constantly on the move and programmed to demolish anyone in her way.

But there is an odd, even creepy, undercurrent in Ava’s backstory that is both repellent and under­developed as an idea.

The film opens with a memory of Ava’s father (Stephen Lang) killed by a couple of gunmen who are then shot down by Ava. Who and what and where and why go largely unanswered. But Ava’s narrated recollection about not shedding a tear over dad’s death makes sense: in later flashbacks it’s clear Lang’s character was quite perverse in the way he trained her to be a lethal weapon.

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The present-day tale finds Ava trying to be a happy newlywed on a Caribbean honeymoon with husband Derek (Cam Gigandet). But a strain of reactionary violence in her won’t hold still: She takes out a dozen people at a dance club and, when Derek mysteriously disappears, there is hell to pay for anyone involved.

One might wish for a little more insight into the killer inside Ava, but it’s not to be. Director John Stockwell throws his energy instead into devising original action sequences (a scene on a zip line in which Carano dangles well above treetops is impressive) and trying to make sense of a bizarre third act.

Throughout, Carano is appealing if not charismatic as an action star.

She certainly deserves better than “In the Blood.”

Tom Keogh: tomwkeogh@yahoo.com