Ian Lowe (left) and Kyle Branzel (right) in Murder for Two at Philadelphia Theatre Company. (Photo by Jim Cox)

This little musical, a recent hit off-Broadway, is a chamber-sized murder mystery with a small cast. The character of police detective Marcus Moscowitz is played by one actor (Ian Lowe on opening night through June 21; a different actor takes over on June 23) – another (Kyle Branzel) does every other role, including all the suspects.

But, wait – there’s more! In addition to acting and singing, Lowe and Branzel are also the entire orchestra, alternating at the piano, and occasionally playing together.

So the show is a two-hander – but that doesn’t do it justice. There are what look like dozens of hands, arms, legs and feet in perpetual motion (especially Branzel’s, who has a Tommy Tune-like physique and similar flexibility). You could describe Murder for Two as high-energy, but again, that doesn’t begin to cover it. It’s miraculous that these two guys can get through it, let alone deliver the polished work they do. Branzel and Lowe’s talent, charm – hell, their endurance alone – is awesome.

Ian Lowe (left) and Kyle Branzel (right) in Murder for Two at Philadelphia Theatre Company. (Photo by Jim Cox)

Within 10 minutes of the 90-plus minute running time, though, it’s clear that no amount of virtuosity can disguise the slenderness of Murder for Two.

You won’t leave the theatre humming the songs – I’d be surprised it you could hum them while they’re going on.  The jokes are lame. (I’m still puzzling my way through one, something about Weight Watchers and a small penis.) You’ll start to notice that all the various suspects, male and female, seem a lot like Paul Lynde, only gayer. And the whodunnit plot is so convoluted that by the time it’s (sort of) resolved, you won’t care. I gave up long before, and instead pondered the mystery of why one actor will play Marcus through most of the run, and another for the last week.

Oh, well. Did I mention that Murder for Two is also a show-within-a show? Probably I should, though I’m not sure there’s even one show here.

On the (ahem) other hand, there are Kyle Branzel and Ian Lowe. Maybe that’s enough.

Through June 28, Philadelphia Theatre Company at the Suzanne Roberts Theatre, 480 S. Broad St., 215-985-0420, http://www.philadelphiatheatrecompany.org