By Lucy Komisar

One of the stars of this play is not human. It‘s the set for the riotous slapstick comedy put on by (real) British actors about a disastrous production of “The Murder at Haversham Manor” by a fake university drama society. Sometimes slapstick is silly, but this is exceedingly clever.

It‘s co-written by Henry Lewis, Jonathan Sayer and Henry Shields who also act in the play. Director Mark Bell does brilliantly at making everything go so wonderfully effortlessly wrong.

The fake plot is a 1920s murder mystery set in the English countryside. Don‘t think this is Agatha Christie. The first actor falls on entrance. Others try to get onstage, but they can‘t unlock the door. Then there‘s the excellent Greg Tannahill, playing Charles Haversham, a dead man whose outstretched hand keeps getting stepped on. When one character sits on the body, the hand pushes him away.

And so it goes. The aptly named (real) Mischief Theatre presents a collection of glorious theatrical pratfalls that erupt in fast succession. The servant Perkins (Jonathan Sayer) spills scotch in a phone upstairs and it come out a phone downstairs. Cecil Haversham (Dave Hearn), the corpse‘s brother, drinks paint thinner proffered as liquor and spits it out on the body, which jumps. Hearn is very good as the hammy goofy brother.

Inspector Carter (Henry Shields), very British with vest and mustache, directs that the body be placed on a carrier, but it rips and two fellows walk out with just the side rods. The body creeps offstage.

Actors take the wrong props and ignore cues. There‘s a grandfather clock big enough for someone to hide in. Players start repeating dialogue, and the farce falls into hysteria.

But as good as the actors are, an indispensable player is the set, by designer Nigel Hook, in which an upstairs room is held up by a post. As actors bump into it, the upper floor sags, till the point where actors and furniture up there are sliding dangerously.

Also, watch the escutcheon over the door; never let a good escutcheon go to waste.

And by the way, the idea is that the inspector will figure out who killed Charles Haversham. Better call in Agatha.

Sophisticated farce is a terrific art form. I didn‘t like the physical fight between two women both wanting to play one of the fake play roles. Sexist, I thought. But otherwise, I never stopped laughing.

“The Play That Goes Wrong.” Written by Henry Lewis, Jonathan Sayer and Henry Shields; directed by Mark Bell.  Mischief Theatre at Lyceum Theatre, 149 West 45^th Street, New York City. 212-239-6200. Opened April 2, 2017. 5/19/17.