When a nice holiday cruise turns bloody, a detective and failed parent must take down the threat and regain his self-worth.

There does need to be a driving factor, a goal. Getting back your self worth is an outcome not really a goal.

You should make the goal more immediate. Someone he loves is in danger and he must save them.

Are the detective and failed parent the same person? I assume so, because you'd have phrased it as *a* failed parent if they're two different people. I'd also specify whether it's a police detective, PI, federal investigator, or some other kind of detective.