LOWELL — When William Shakespeare bequeathed his wife his “second best bed,” was it an insult, a coded message of love, or a pro forma element in a legal document? Playwright Vern Thiessen, in “Shakespeare’s Will,” combines familiar historical facts with a wholly imagined story of life with the Bard of Avon, delivered from his wife’s point of view.

In Merrimack Repertory Theatre’s production of this one-woman show, Thiessen owes a huge debt of gratitude to actress Seana McKenna, who gives Shakespeare’s wife, Anne Hathaway, a voice and an attitude. McKenna’s performance is so luminous that she consistently lifts the script above its own mundanity.