One thing you learn in this business, never write a good actor off. Whatever trap he or she has fallen into, whatever their overhead has become that drives the sorts of payday pictures they make, the good ones are never more than one expectations-defying role away from reminding you why they seemed special, back in the beginning.

Gerard Butler hasn’t made a Scottish ensemble piece like “The Vanishing” since long before he saddled up on the “Olympus has Fallen” franchise and began collecting “Den of Thieves” checks (he’s doing a sequel to that, too.). He settles nicely into a supporting role in this period piece, a thriller that speculates on a famous disappearance among the lighthouse keepers of the Flannan Isles. 

Three Outer Hebrides lighthouse keepers disappeared in 1900, leaving behind no clue as to what might have become of them. “The Vanishing” leans hard on a very conventional solution, a plot that throws the three men into contact with a treasure.

Introduce a little gold into the equation, and you’ve got “The Treasure of Sierra Madre” at sea, on an island — a tale of greed, treachery, mistrust and bloody violence.

Veteran character actor Peter Mullan is Thomas, the widowed senior man at their remote station. Connor Swindells (sharp, naive) is young Donald, the new guy learning “the ropes.” And he’s to learn the care and maintenance of the light, maintenance that includes handling deadly quicksilver that was used to lubricate the rotating Fresnel lens.

James (Butler) is the experienced man, the one with the family,  and a sense of humor.

“What does this do, then?”

“It’s a foghorn.”

“When d’ye use it?”

“When it’s foggy, Donald.”

The two old hands josh the new guy as they pluck dinner out of the crabs in the surf, check the anenometer (wind gauge) to log the weather conditions and struggle with the balky radio (the time setting has been changed from the real disappearance) that works a fraction of the time.

Their routine is shattered the moment a rowboat washes up in the rocks. A Nordic looking brute is washed up with it. With a small trunk. Sending the new guy down to check on him rouses the “drowned” man to a fury, and only Donald’s desperation saves him. The cast away flipped out that they were taking his chest.

Old Thomas is the first to look in the chest. He doesn’t share what he saw in it with the others, but they figure it out soon enough. Donald is racked by guilt, James by curiosity. But what Thomas realizes is that the gold the man had with him and his paranoid, to-the-death defense of it means others will coming looking for it — and asking questions. And they’ve got the chest and a body on their hands.

He sees the inherent threat in their situation and gives orders accordingly — “Do exactly as I say,” and “All you have to do is keep your bloody mouth shut.”

Things never work out the way the experienced hand plans. The island is visited, the visitors are menacing and the lies the fellows tell let them down. With just a gaff hook, a hatchet and shovel to defend themselves, they’re in deep before they even realize they’re in at all.

Danish director Krystoffer Nyholm doesn’t clutter “The Vanishing,” keeping it a stark, brutal thriller, a morality tale that reminds us that taking a life never comes easily or can be taken lightly.

The violence here is brutal, savage and personal — and filled with regret.

I’ve been a fan of the gruff, working class tough Mullan (“Hostiles,””Welcome to the Punch,” “Sunshine on Leith,””Tommy’s Honour”) for years and this makes a grand vehicle for his brand of Scots crustiness.

Butler sheds the bravado of too many years in Hollywood actioners and finds a family man torn by remorse, greed and the madness that can come from violence only given consequences after the fact.

The brogues are thick enough to warrant subtitles, but the actions are so primal as to require no dialogue to follow every wrinkle in the plot, every nuance in the tragedy we see unfold.

“The Vanishing” manages to shock even as it fails to truly surprise, a movie that takes a worn situation and wrings fresh pain out of it as it reaches — over-reaches — to solve a mystery that is probably even more mysterious than whatever the screenwriter’s cooked up.

And in taking a step away from the one-liners, the shootouts and B-action movies, Butler reminds us of the soulful Scot he used to play before “300” made him an action hero.

MPAA Rating: unrated, graphic violence

Cast: Peter Mullan, Gerard Butler,Connor Swindells, Søren Malling and Ken Drury

Credits: Directed by Kristoffer Nyholm, script by Joe Bone, Celyn Jones. A Saban Films release.

Running time: 1:43