This is a knockout of a production showcasing two tiptop actors, Lenny Haas and Kate Hurster, in a shrewd adaptation of Henry James' classic story The Turn of the Screw. Jeffrey Hatcher (Compleat Female Stage Beauty and Three Viewings) wrote this clever script, genuinely dramatizing the famous tale of a governess who wigs out while looking after two children at a 19th-century manor house. Is the story about Victorian sexual repression and its terrible and weird consequences, or about real ghosts? In most productions of this much-adapted, much-filmed work somebody usually decides — show the ghosts (in which case she's not nuts and we are) or don't (in which case she is and we're not). Luna's production, directed by Gregory Scott Campbell, happily votes with James: all of the above. Ambiguity isn't Henry James' middle name for nothing. The clever tone here hovers between old-fashioned melodrama and a whiff of parody. Cue the spooky music.

There are at least six characters — and Haas plays all but the governess. He introduces the scene as the narrator, then becomes the seductive uncle who lives in London and hires the governess with the proviso that she never bother him about the children. He also plays Miles, the precocious and slightly creepy, slightly pitiable 10-year-old (his little sister, Flora, cannot, or will not, speak, which is convenient for these dramatic purposes). Haas also plays the old biddy of a housekeeper, as well as providing a variety of sound effects: kingfisher, wind-ruffled pages of a book, rain dripping, etc. He gives every character not only a different accent, but a different voice pitch and a different posture. It is a virtuoso performance, but no more so than Hurster's romantic, impassioned governess.

On the little stage, there are only an oriental carpet and a carved love seat. The lighting (designed by Joshua Schulman) shifts from suggesting indoors to outdoors, daytime to nighttime, and the costumes (designed by Barbara Campbell) are both elegant and oddly all-purpose.

The problem in any adaptation from page to stage is what to do with all the literary stuff: the description of the scene, the passage of time and the characters' thoughts — all of which imply point of view (well, in a Jamesian world, what doesn't?). Hatcher builds all this in quite handsomely, and the presence of the ghosts of the evil (or maybe just sexual) Peter Quint and his lover, the former governess Miss Jessel, is vividly but obscurely suggested. It's creepy enough to hold you for a Halloween treat, and theatrical enough to impress you with how much can be accomplished by talented people in 75 minutes.

Turn Of The Screw Through Nov. 13, Luna Theater Co., Theatre Studio 5, 825 Walnut St., 215-704-0033 or www.lunatheater.org