Brendan Gleeson is to John Michael McDonagh as Robert De Niro is to Martin Scorsese. That's not to say that Gleeson is De Niro; it's just that McDonagh's words and direction bring out the best in Gleeson, just as Scorsese made De Niro shine throughout the 1970s and 80s.

In McDonagh's Calvary -- the follow-up to his terrific The Guard -- Gleeson plays Father James Lavelle, an Irish priest who's threatened by a parishioner. The man begins his confession by describing his long-ago molestation at the hands of another priest in gruesome detail, including the first time he tasted semen. “Certainly a startling opening line," Father Lavelle notes, Gleeson's face betraying its first leaks of unanticipated emotion.

He then explains to the Father that he's going to murder him. Not because he's a bad priest; because he's one of the good ones. Despite making this threat during a relatively exposed confession, the would-be assassin doesn't try to hide his voice. He also tells Father Lavelle where it'll happen: on the beach, a week from the day. Is he daring the priest to attend his own execution? Is he going to hunt Father Lavelle down? Is the threat an idle one? We're left to wonder.

The rest of Calvary covers what may end up being the final week in Father Lavelle's life. His daughter Fiona (Kelly Reilly) returns home after a suicide attempt. He intervenes in a love triangle of sorts between the town butcher (Chris O'Dowd), his gleefully sinister wife (Orla O'Rourke) and her unconcerned lover from the Ivory Coast (Isaach De Bankolé). He converses with a twisted physician (Aiden Gillen) and grows increasingly frustrated with a piss-drunk millionaire (Dylan Moran) who seems to be seeking half-hearted absolution for his sins.

Father Lavelle confesses to a superior early in the film that he has an idea as to which of his parishioners made the threat. But he never makes an accusation or (as far as I could tell) acts concerned around his potential murderer. Instead, he unravels, seemingly overwhelmed by all the varying degrees of evil he encounters on a daily basis.

Much as Richard Jenkins and Frank Langella made the unexpected leap to leading man at an older age, Gleeson has become a full-fledged master at his craft. It began back in 2008 with the Colin Farrell resurgence project In Bruges, written and directed by John's brother Martin. He followed that up by charming us all as a stone-faced hedonist cop in The Guard, the aforementioned first feature from Calvary's McDonagh.

And here, he perfectly embodies a conflicted priest who isn't quite sure where his particular brand of religion fits into modern society. He mocks the other priest in his parish for lacking a backbone but allows doubt to creep into his voice when asked about the complexities of "thou shalt not kill." He cares for his daughter deeply but can't seem to understand how, despite being physically present, he abandoned the family after his wife died.

Gleeson, sort of like an Irish Bill Murray, has a comic darkness to him. His weathered face betrays a weariness that's often played for laughs, especially in previous films by the Brothers McDonagh, but in Calvary he's been worn down beyond humor. A past that's not his own has come to claim revenge, and he's forced to confront his own buried demons in the process.

There's something about snappy dialogue in an Irish brogue that grants it extra power; McDonagh provides his cast with enough brilliant, bleak rejoinders to pack two movies about death, pedophilia and adultery. A lengthy monologue from Gillen's Dr. Harte on the horrors of using too much anesthesia, in particular, expertly toes the line between entertaining and unbearable. The Irish are at their best when they're bantering about hopeless topics with grim smiles on their faces.

The Guard was a clever romp; its darker moments were in service of the story and nothing more. But in Calvary, McDonagh grapples with morality in an oft-immoral world. What if you're sentenced for a crime you didn't personally commit? Do you run from what's coming, or do you stand tall and, if necessary, pay penance for the sins of others? Or your own sins, no matter if the punishment doesn't quite fit the crime?

Father Lavelle preaches forgiveness, and he also embraces acceptance. The Jesus parallels are ample in Calvary (the film's title references the site where Christ was crucified) but there's no rising from the dead for these characters. They're hopeless, or at least they choose to be, and McDonagh doesn't seem to see a difference.