The set-up:

The Joe Mantello adaptation of David Sedaris's recounting of his stint as Crumpet the Elf, a holiday job at Macy's in New York City, returns to amuse us with the underside of the Christmas Spirit.

The execution:

The set is a square, anchored at one corner by a giant red Christmas ornament, at another corner by several life-size penguins, and at another by a chair into which an exhausted Crumpet crumples at times, only to spring alert as he returns to the demanding duties of Santaland.

Todd Waite is the sole inhabitant of the stage and must be the tallest elf in Elfdom, but that matters little as he is a master at the fixed stare of consternation and adept at the double-take of disbelief at the horrors beneath the white cotton snow.

His expressive face lets us see in no uncertain terms what is going on, and what may be lost in nuance is gained by the explicitness of his delivery. His unflagging energy serves this play of about an hour well, and he delivers in spades the growing sense of panic as the shopping season reaches its peak.

The humor is rich, and there is a lot of it. The discovery that Santa is an anagram for Satan leads to some original and amusing insights. It is directed by David Cromer, who keeps the pace dynamic and the humor flowing.

The verdict:

No Christmas is complete without an Elf, and Todd Waite fills the gap admirably as he captures the dark and highly original humor of The Santaland Diaries.

The Santaland Diaries runs at the Alley Theatre, 615 Texas Avenue, through December 31. For information or ticketing, call 713-220-5700 or visit www.alleytheatre.org.