Adult Onset is a 2014 novel by Canadian writer Ann-Marie MacDonald. Set in The Annex neighbourhood of Toronto, the story centers on one week in the life of a successful writer of young adult fiction, Mary Rose MacKinnon, who finds herself taking care of her two young children while her wife is out of town directing a play. The novel starts with a light tone in describing Mary Rose's new-found solo daily domesticity with her son and daughter. But through a series of flashbacks, "Mister" or "MR" as Mary Rose is known to family and friends, is forced to confront her own repressed abuse as a child. At the center of the family drama is her mother, Dolly, an immigrant child-wife in postwar Canada.