Brie Larson, right, as Ma and Jacob Tremblay as Jack appear in a scene from the film, "Room."(George Kraychyk/A24 Films via AP)

Jack starts most every day of his life the same way. He very systematically greets every object in his room, and today is no exception. But today is a very special day. It’s Jack’s fifth birthday.

What begins as a sweet moment between mom and son, baking a cake, leads to the nerve-wracking, psychological thriller that is “Room.”

Jack’s mom, played by Brie Larson, has been confined to this single room for going on seven years. She gave birth and raised Jack, played by Jacob Tremblay, within these four walls for his entire life.

Mom convinces Jack that the world consists of only their room, and that her captor is a kind of benefactor who occasionally brings them their food and clothes. Their one link to the outside world is an old TV with lousy reception, and Jack understands that what he sees on the tube is just more make-believe, like the bedtime stories his mom tells him every night.

But now that he’s turning 5, mom has decided Jack’s ready for a little dose of reality.

“Do you remember how Alice wasn’t always in Wonderland?” she asks her son. “I wasn’t always in a room. I’m like Alice. Now we got a chance.”

Mom and Jack begin plotting an escape. That’s the nerve-wracking premise of “Room,” a fascinating psychological thriller about the lengths to which a parent will go to protect her child, and the consequences of those lengths. How does one possibly cope with being confined to a single room for years? How does a mother squelch her own fury at the injustice thrust upon her in order to cater to the needs of her growing child? And what does it do to a child’s psyche to suddenly realize his entire concept of the world is completely and utterly wrong.

This is a very narrowly focused film that very naturally broadens out to encompass many relatable themes far beyond the trauma of this particular woman’s extreme situation. “Room” speaks volumes about, not only the intimate bond between mother and son, but also about the dynamic between parents and adult children, between husbands and wives, and even between grandparents and grandchildren.

The role the media plays in our lives even gets a serious look.

Ultimately, this is a very clear-eyed look at the emotional crises engendered by tragedy and the capacity of human resilience to cope, in spite of all.