“Unholy Communion” is a lukewarm mystery-thriller about a hot-button topic.

A serial killer exacts vengeaunce on child-molesting Catholic priests in the aftermath of what used to be the biggest sex scandal in history.

These days, with a pedophile-tolerant Catholic-packed Supreme Court protecting the Pedophile in Chief and untold scores of fellow predators and accomplices, and their enablers in Congress, we don’t hear much about the thousands of crimes and the parrish-shuffling pedophile priests that were the church’s cover-up of choice any more.

The mystery in this “Communion” is obvious, stripping any hope of suspense. The situations and settings are generic and the performances are generally tepid. So save your prayers for this one.

It’s a Minnesota Iron Range (filmed in Minneapolis) tale of decades of abuse bringing murderous revenge down on the small town of Scandia.

Adam Bartley of TV’s “Longmire” is Chris, police chief in a two-cop town, the sort of softy who takes home the first murder victim’s retriever to his wife (Iréna Flury) and kids.

The testy county CSI agent (Laura Espring) and pedantic medical examiner (Casey E. Lewis), whom the agent loathes, will be Chief Majek’s only real help in tracking down whoever made Father Doyle (Patrick Thomas O’Brien) eat his rosary beads before shooting him in the head.

Sepia-toned flashbacks to the priest’s criminal history send the message that he had it coming. He won’t be the last. A little priest-to-choirboy Latin is the clue that sets that up.

Writer-director Patrick Coyle (“The Public Domain” was his) serves up side orders of domestic strife involving the department dispatcher (Bridgett Thompson) and her potentially violent husband, and the couple that the chief and his wife set-up, played by Laura Robards (Jason Robards’ granddaughter) and Vincent Kartheiser.

There’s even a transgender ex-lover (Dee McLaughlin) in the mix, none of which muddies the waters in a story where we’ve seen the killer in the first scene and later and there’s virtually no police procedural tropes to make this a “Columbo” styled “Will he get away with it?”

Indie cinema is where we get most of our movies that look and sound like America outside of LA and NYC. But indie films that work are as rare as studio pictures that come off, and this one doesn’t.

The premise is solid and the casting isn’t bad. But there’s no pace, no urgency to the performances and precious little to grab hold of and invest in here. Even the conflicted Catholicism of some of the characters is half-hearted.

It’s a shame, because this subject is still potent and “Primal Fear” came out a long time ago, and movies such as “Sleeper” and “Righteous Kill” approached the subject more gingerly than one would like, the one mistake “Unholy Communion” doesn’t make.

Rating: TV-MA, violence, profanity

Cast: Adam Bartley, Vincent Kartheiser, Bridgett Thompson, Iréna Flury, Laura Espring and Patrick Thomas O’Brien.

Credits: Scripted and directed by Patrick Coyle. A Freestyle Release on Amazon Prime.

Running time: 1:33