WHAT’S the proper way to act when someone close to you dies? Do you cry uncontrollably? Lock yourself away and not speak to anyone? Do you carry on as if nothing happened? That’s one of the central themes of Kenneth Lonergan’s quietly devastating drama.

When his brother Joe (Kyle Chandler) suddenly passes away from heart failure, reserved building janitor Lee (Casey Affleck) returns to his old town of Manchester, Massachusetts to break the news to his 16-year-old nephew Patrick (Lucas Hedges).

While trying to take care of his brother’s funeral arrangements and financial affairs, he discovers that in his will he planned for Lee to become Patrick’s guardian, a responsibility for which he is entirely ill-equipped to handle.

On the surface, not much happens here plot-wise. But bubbling away underneath is a world of pain, hurt, uncertainty and aching loss that is exquisitely communicated on-screen by Lonergan’s pitch-perfect control of tone and the understated yet powerful performances that populate its narrative.

Rarely since TV’s Six Feet Under has a piece of drama captured the singular effect of loss on those that are left to pick up the pieces and how it affects everyone in their own unique ways. From the delayed moment it takes for the sorrow to truly hit home, to the awkward and funny small-talk that exists to alleviate tension.

This is particularly true of our central character, whose grief is compounded by the fact that he never got to say goodbye to his brother after arriving too late to the hospital.

Affleck brings a magnificent subtlety to him in one of his best performances to date. He projects an image of depleted devastation, rather than screaming outrage at the unfairness of death. His performance is made all the more powerful because there are no big Oscar-bait speeches but rather a discreet, introspective suffering.

Hedges avoids maudlin clichés of the grieving son to give us a believable, compelling portrait of an impressionable teenager suddenly rendered father-less. Michelle Williams creates a shattering impact with a limited but important role as Lee’s ex-wife Randi.

It’s a film about gradually and patiently peeling away the surface loss that runs so deep that it becomes unthinkable to even mention it beyond the logistics of what to do next. Its flashback structure may be familiar but is used in a powerful way to both punctuate present day goings-on and illuminate the characters’ pasts. Is one loss felt greater than another or do they merely combine together over time, creating fresh wounds that deny true healing?

This emotional tour de force explores this theme and much more in a way that seemingly doesn’t make a fuss but creeps up on you with a rare raw power.