Nigel Reed in “The Woman Who Amuses Herself”. Courtesy Theater Alliance.

So what was Mona Lisa really smiling about anyway? Was she thinking about a past romantic rendezvous? Wistfully reminiscing about days gone by? Wincing a little over a pesky toothache?

Hearing third graders provide their theories on the eternal question (yes, that’s where the toothache theory’s coming from) is a chuckle-worthy aside during in Victor Lodato’s The Woman Who Amuses Herself, now getting the Theater Alliance treatment over at H Street Playhouse. Overall, though, amusing vignettes can be hard to come by during this meditative – and, to be frank, slow-moving – work.

The premise is undoubtedly intriguing. Woman means to get behind what “really happened” when museum worker Vincenzo Peruggia impulsively decided to steal the iconic painting from the Louvre back in 1911, and house it in his apartment for two years. As Peruggia coexists with the painting, reality blurs for him, and he begins treating Mona Lisa like an enigmatic, flesh-and-blood woman who haunts him, rather than as a piece of art. The Woman Who Amuses Herself is a portrait of a man obsessed and unraveling.

Getting inside Peruggia’s head starts off as a fascinating, even seductive experience, but his decent isn’t compelling enough to sustain interest over a two hour time period. And while the play’s lone actor, Nigel Reed, inhabits Peruggia with a pitiable, aching passion, Reed doesn’t disappear nearly as convincingly into the nine or so other characters he must embody over the play’s duration. And with the exception of those precocious third-graders, appearances from say, artist Marcel Duchamp, or an old Italian woman, just feel like they’re cluttering up the story.