Okay, here goes for the Three Tall Women spoiler. Someone please correct if I have the details wrong.
And OBVIOUSLY THIS IS A SPOILER.
There are actually two coups de theatre in this production. Joe Mantello, the director, and Miriam Buether, the set designer, are at the top of their game here.
The first act takes place in the bedroom of a rich woman's apartment, and at the very end of the act, the rich woman, played by Glenda Jackson, is lying in bed and has a very bad stroke, possibly bad enough to eventually be fatal. As the second act curtain rises, we see the same apartment, but now the back wall has been replaced by glass, and behind the glass is the mirror image of the apartment, with the exact same furniture but arranged like it is seen in a mirror. For example, the bed is facing the audience in the original bedroom, and it is facing upstage in the mirror image bedroom, with the two heads of the bed virtually touching each other. (The headboard disappears with the wall.). The chairs, lamps, tables, etc are all also arranged as if you are looking in a mirror, but you aren't, because the divider is glass. Then at the far end of the mirror image apartment, there is an actual wall entirely mirrored, so you can see the image of both the original apartment and the mirror image apartment reflected back, in almost a fun-house kind of way. And you can see the audience reflected back as well, which I'm sure is intentional.
The original apartment does not seem unusually shallow in Act One, but it takes up less than half the depth of the stage,. But it really isn't obvious that there is something behind, especially something that seems really deep with the entire back wall being mirrored, so everything is reflected and re-reflected. It's pretty stunning when the curtain goes up. So the revealing of the mirror upon mirror of the apartment is the first coup de theatre.
The very first lines of the second act take place in the mirror image apartment between Alison Pill and Laurie Metcalf. They refer to the Glenda Jackson character lying in bed, but from my seat pretty far in front, I couldn't actually see anyone lying on the bed (the pillows are quite heaped up). But pretty quickly, Pill and Metcalf come into the original apartment, joined by Glenda Jackson coming in from the wings. Then, for the rest of the second act, the three women stay in the original apartment, with the son's arrival occurring in the mirror image apartment. And every so often, the three women step out to the bare stage in front of the actual apartment set to give their monologues.
The final monologue is by Glenda Jackson, talking about how the happiest moment is when we finally die. She has incredible presence, and when she steps out onto the bare platform to give this speech, she is spellbinding. And in the last fifteen seconds, while she is talking about welcoming death, the entire back mirrored wall tilts, so that it is no longer reflecting the audience but now reflects the bed, and lying in the bed is an incredibly realistic mannequin of Jackson's character, awaiting death. The moment of death turns from the public (reflecting the audience) to the intensely personal (reflecting just Jackson's character). I think Mantello and Albee are saying that death is a moment you go through alone. Jackson's voice fades away, and the lights come down.
There is no indication that the mirrored wall can move before that, so it really is a coup de theatre. And the wall is huge. It covers the whole width of the stage and is probably twelve or fifteen feet high, maybe more. I was the person who earlier said I had mixed feelings about the material, but those two moments were unforgettable. It was even more powerful because I didn't know that there was a body in the bed before that. I'm sure the mezzanine viewers can see it throughout the act, but I don't know how much of the orchestra can see it before the end.