Sean Ramey as The Creature, Marie Stewart Harmon as Mary Shelley and Tyler Costigan as Percy Shelley in Kevin O’Leary’s “Anonymous.” Photo by Kat Moraros Photography

He might have missed a travel connection and arrived a few days late for Halloween. But Frankenstein’s monster is now in the house at the Studio Theatre at Portland Stage for a brief run of Kevin O’Leary’s gripping new play “Anonymous.”

Though he appears on stage, The Creature, as he’s called in the program, is being born in the mind of a fledging author as she tries to come out from under the daunting reputations of her famous parents, defy the limitations placed on female artists of the early 19th century, and create something new and important.

The three-actor, 90-minute play (with no intermission), directed by Lauren Stockless, concerns the struggles of Mary Shelley, the teenage author of “Frankenstein,” the famous and influential 1818 novel that gave birth to ideas about modern life in all its complexity. The play focuses on the psychological and emotional aspects of the author’s challenges as she tries to juggle the demands of new motherhood with a powerful drive to complete her work.

Marie Stewart Harmon as Mary Shelley.

She’s continually hindered by her suspiciously solicitous husband, the poet Percy Bysshe Shelley, and the creature of her imagination who won’t quit asking difficult questions and demanding answers. The creature, of course a projection of the author, wants a unique voice, not only in a literary sense, or things may get ugly for both.

Marie Stewart Harmon, fresh from a major role in Mad Horse Theatre’s production of “POTUS,” gives her Mary the troubled yet determined persona of one who’s seeking to form an identity of her own in a male-dominated world. Like the creature she created and now imaginarily converses with, she is pursuing the “freedom to live” on her own terms.

Tyler Costigan plays Percy as a bit of a fretful fop who can’t ever seem to find just the right last word in an argument before he storms offstage to fetch tea and brandy for his wife. In what may be one of the most handled prop babies in theater history, Percy and Mary pick up and put down their child repeatedly, reflecting both ambivalence and ultimately distress.

Harmon, Costigan and Ramey.

Sean Ramey is riveting as The Creature. Not overly monstrous in appearance, he nonetheless creeps around the minimal set (and into the audience area), examining things, and creating a sense of menace that never quite completely goes away, even in the play’s few humorous moments. His “innocence” has a dangerous appeal. Like the baby, he pulls at a conflicted Mary.

The period costumes by Michele Lettiere situate the action while the quick-changing lights by Michaela Wirth allow for points of entry into the novel itself. Recorded piano and violin music effectively supports the unsettling mood of the play.

Captivating and a little freaky, O’Leary’s latest play brings an important moment in literary history to life.

Steve Feeney is a freelance writer who lives in Portland.