Entertainment

At home with Alice & Co.

You’ll discover what it feels like to disappear down a rabbit hole at “Then She Fell,” the fiendishly clever immersive theater piece inspired by the life and writings of “Alice in Wonderland” author Lewis Carroll.

This dreamlike event, presented by Third Rail Projects — and performed in a wing of the former Greenpoint Hospital in Brooklyn, abandoned 30 years ago — is an experience you won’t soon forget.

Fifteen people at a time are guided through a series of intricately designed spaces dripping with atmosphere. Along the way, they meet Carroll, Alice, the White Rabbit and the Hatter, who turns out to be very mad indeed.

After passing through an elaborate courtyard garden, you enter a waiting area, where you’re greeted by uniformed nurses and given a set of keys that unlock boxes and cabinets you find along the way.

You then proceed — both in small groups and sometimes, tensely, on your own — through the haunting spaces to the accompaniment of ominous music and sound design.

Much of the action is of the choreographed variety, with the characters engaging in athletic and frequently erotic solo dances and pas de deux. At other times, you witness dramatic scenes and take part in them yourself. You’re made to lie down in a bed while being read a bedtime story. A beautiful young woman asks you to brush her hair as she engages you in an intimate conversation about love. You play a poker game that turns out to be rigged — and you’re offered “elixirs” of heavily spiced wine and tea to drink.

A lingering theme is Carroll’s obsession with the pre-pubescent Alice Liddell, on whom Alice was based. Scattered throughout the rooms are yellowed pages of letters and poems that he wrote to the young girl.

Digging on your own, you may find this haunting note that her mother wrote Carroll (real name: Charles Dodgson): “Dear Mr. Dodgson, I regret to inform you that my daughter will no longer be able to accept your letters. Yours . . . L. Liddell.”

The hospital’s past is evoked in rooms filled with horrific looking, old-timey medical instruments and X-rays of animals on the walls.

The performers inhabit their roles with an almost uncomfortable intensity, giving you the sense that you’ve only just happened to wander into their spooky playground. They’re all terrific, particularly Elizabeth Carena as the Hatter, who fits you with gaudy headwear while chattering manically.

Brilliantly designed and directed by Zach Morris, “If I Fell” is a much more relaxed and intimate experience than Emursive Theater’s wildly successful “Sleep No More.” Here, you don’t rush around in packs, trying to keep up with the performers. Best of all, you don’t have to wear a damn mask.