It’s sure nice to have Mel Gibson back on the big screen carrying a gun, seeking revenge for the death of a loved one and quivering with righteous rage. But after seven years off-screen what a shame he couldn’t find a better script. “Edge of Darkness” is a mess. Convoluted, poorly structured and lacking in the important emotional turning points and character moments necessary to make this kind of thriller work.

Gibson plays Boston Police Detective Thomas Craven, an honest cop and inattentive but loving father whose 24-year old daughter Emma comes home for a visit. Things are warm, if a bit strained between them, but she’s ill — violently ill — and on their way out the front door to the hospital she’s shotgunned in a drive-by shooting that was meant to kill him. Or was it?

The plot’s entirely too ambitious, involving defense contractors, corrupt Senators, leftist activists and a gentle yet menacing wine-sipping government fixer named Jedburgh (The Mighty Ray Winstone) whose loyalties shift all-too obviously when the plot requires a nudge — when the screenwriters are stuck. In the “Austin Powers” trilogy he would’ve been called Agent Exposition.

Wintsone continues his perfect record of making everything he’s in better, and Jedburgh is a very interesting character. You do want to know more about him. The problem is that there’s no natural place for him in the film’s narrative. He reminds me of  Liev Schreiber’s mysterious John Clark in “The Sum of All Fears.” Another movie where a mysterious supporting player in a disappointing film comes off as though he’s visiting from a much better movie.