Florian Zeller is interested in varieties of derangement and their consequent losses: of time, of memory, of reality. His "Family Trilogy"--THE FATHER was on Broadway a few years ago and THE SON just opened in London--depicts mental collapse as a process whereby minds become bare. At its heart, THE MOTHER is a demonstration of depressive psychosis and it should be devastating. It isn't. Zeller wants the audience to be as confused, as dislocated as the mother in question. This is his regular narrative strategy in these plays, but it's less effective here because the story is a generically, broadly Oedipal one and because Huppert, a bold and daring actor, doesn't have command enough of English to be anything more than distracting. Her line readings just sound loopy and they keep you outside of the play. If you like Zeller, you'll want to see this nonetheless. Otherwise, wait for THE HEIGHT OF THE STORM which is coming to Broadway in the fall and is heartbreaking.