The strange experiment known as in3 takes over the whole black-box space of Exit Stage Left; you sit among a group of people who clamber up columns and stand on overhead platforms, lie on the floor and move as if they're walking underwater, and recite broken fragments of meaningless dialogue. ("What are you doing?" "I gotta check something." "I thought you just did that." etc.) Certain coherent images resolve out of the dim-lit confusion -- a gravedigger, a madman raconteur -- but in general the show is an act of choreography, weaving music and words with slow-motion gesture. The weirdest thing is, it works. in3 might feel too long, even at just over an hour, but Jason Craig, Sara Kraft, Parnell Klug, and Michelle Talgarow (and Meredith Eldred directing) do a good job of convincing us we've walked into another person's dream. In fact, the dialogue and some of the movement seem drawn from a dream journal -- meaning it isn't tendentious or forced -- and David Molloy's slow, sad, clanking melodies on a modified piano cast an eerie spell. If shows like this easily devolve into boring nonsense, in3 is a pleasant surprise, like watching the children of Laurie Anderson come up with some new ideas.