David Mamet's potty-mouthed lesbian period piece, Boston Marriage, is an odd duck. In a weird hybrid of Mamet acerbity and formal Victorian flourish, characters toss around terms like "twat" and "douche" while delighting in sweetmeats in the drawing room. It's either an interesting conceit or a hollow contrivance. Possibly both.

"Boston marriage" is a 19th-century term denoting households in which two unmarried women live together in sexually ambiguous independence. In this case, the informal brides are Anna (Kate Myre) and Claire (Peggy Gannon), two upper-class women past their prime, wrangling with the unfortunate necessity of male financial support and the uncertain future of their union. But there's no ambiguity about the sex part. When Claire comes home one day and announces that she's fallen in both love and lust with some young girl, it throws Anna into a tailspin of jealousy, calculation, and verbal revenge.

Mamet's dialogue is frothy but sharp, a masterful combination of comedy and emotional abuse. Anna and Claire torment each other, themselves, and, most frequently, Catherine (Heather Persinger), the Scottish housemaid whom Anna unremittingly accuses of being Irish ("Do you know why you people died in your precious potato famine?"). The three actresses do their jobs well—Catherine is a homesick puppy, Claire is obliviously libidinous, and Anna is cruel yet vulnerable. We hear about the other characters (the girl of Claire's affections, Anna's philandering patron) but they, and the complicated plot, are really just an excuse for Mamet's pile of words, words, words.

Boston Marriage is funny, to be sure, but it's sometimes difficult to find the humanity beneath the rapid-fire repartee. There's plenty of bite, but not much dog.