To call this bizarre comedy by English playwright Anthony Neilson a departure from Third Rail Rep's usual fare is inadequate. The first act of The Wonderful World of Dissocia contains, among other oddities: a musical dance number featuring soft-shoe, hip-hop and high kicks; a flying car, a speaking goat and polar bear and an accordion-playing hotdog. For a company with a penchant for witty, slightly maudlin black comedies and dramas, this isn't the same planet.

Maureen Porter stars as Lisa, an English musician who is visited by a creepy Swiss gent who tells her the reason she's been feeling out of sorts: During an international flight, she somehow lost an hour. To get it back, she must travel to Dissocia, a land made up of puns and sight gags, under siege by the sinister forces of the Black Dog King. Her manic adventures over the following hour share an obsession with puns and a childish delight in violence. While many are enjoyable, most of these scenes, which Neilson created with the help of a troupe of improvising actors, are far too long and loud. I don't know if Neilson was intentionally triple-underlining the madness or whether he's just incapable of killing his darlings and left in every cockamamie idea that came out of scene work. Either way, it's annoying. At intermission I told my wife I thought it would take a sharp tonal shift to save the evening from being a total waste.

That shift came more abruptly than I'd imagined: I won't spoil the surprise, but suffice it to say that my suspicions that Dissocia was just too nutty to be serious were not baseless, and that Dissocia has more in common with the company's usual tastes than it seemed. The show mostly justifies its mania. This is the largest show Third Rail's attempted, employing seven of its 12 acting members, and probably the most technically demanding. Their accomplishments, from the set to the dance routine, are impressive, no matter one's opinion of the material. The set, lighting and sound design are excellent; the cast seems tireless. Porter, who spends two exhausting hours without leaving the stage, deserves a medal.

SEE IT: World Trade Center Theater, 121 SW Salmon St., 241-5410.
7:30 pm Thursdays-Saturdays, 2 pm Sundays. $15-$32.