Margaret (Rachel Griffiths) is a divorcee running a small shop on the outskirts of Dublin. She doesn't do much; not only does she not interact with her employees, but she doesn't go out with friends or date either. When her ex-husband shows up on her doorstep, saying that their 18-year-old son is missing, she barely bats an eye - after all, she left her family when her son was just a baby. When it turns out their son died drowning in a canal, her ex spirals into grief. In what seems like an act of latent pseudo motherhood, she takes in a homeless young man around her son's age. Only things don't exactly develop with a mother/son bond . . . instead, the two start a full-blown sexual relationship that will either help them both heal or will totally annihilate them. Griffiths strips down more than once, showing full nudity when she bones her newest roommate in a bathtub and then again in bed, plus a great shot at her breasts when she goes for a dip at the community pool. It looks like the star of Mammal really does like to do it like they do on the Discovery Channel!