Maybe the most devastating thing about “The Father” is that what it depicts is really a best-case scenario for someone with a memory disorder.

Andre (Craig Johnson) is loved, comfortable and well cared-for but, as this unsettling play makes clear, his life is a kind of cage. Billed as a “tragic farce,” Gremlin Theatre’s “The Father” plays like an absurdist comedy in its opening scene, which finds Andre and daughter Anne (Miriam Schwartz) bickering affectionately in a conversation that begins to reveal the difficulties Andre is having while also planting a few mysteries.

Why is Anne put off by mentions of her sister? What will become of Andre if Anne leaves Paris to move to London? Trying to hold onto my optimism, I even briefly wondered: Is it possible Andre is fine and the other characters are gaslighting him?

Spoiler alert: He’s not and they aren’t. After that opening, everything resets in each succeeding scene. Rooms gets rearranged, new characters are introduced (not always played by the same actors) and, perhaps as a visual metaphor for Andre’s brain, the stage gradually empties of furniture.

French playwright Florian Zeller, whose script was adapted by Christopher Hampton (“Les Liaisons Dangereuses”), allies the audience with Andre, making us as disoriented and scared as him, and even planting a clue to appreciating the play: “I like taking people by surprise,” the usually mild Andre says after he suddenly turns nasty. “It’s a special brand of humor.”

The acting in “The Father” also wants to keep us on edge. Ellen Fenster has directed Johnson to behave as if he’s in a different play than everybody else — his a light comedy and theirs a drama of despair.

“I didn’t even know I could tap-dance,” Johnson’s Andre says with guileless delight, a sad/sweet peak in a beautifully modulated performance that builds in increments to the finale we know must be coming, given Andre’s vicious disease.

Andre is either unaware of what’s happening or in denial about it, but Anne functions as the audience’s eyes. Through Schwartz’s empathetic and detailed performance, every moment feels connected to what comes before and after it, and we appreciate what is being lost as Andre’s light dims.

“The Father” is a polished and surprisingly entertaining production of a play that’s not great. The resets effectively bring us into Andre’s brain but they begin to seem gimmicky because Zeller doesn’t play fair: While the play takes Andre’s point of view, sometimes we’re shown scenes to which he’s not privy.

The dialogue doesn’t always ring true, either. What loving daughter would ask a man suffering from memory loss, “Don’t you remember?”

He doesn’t, of course, and that’s both the tragedy and farce in this compelling, if uneven, play.