Who can be a mother? What makes them a mother? Do we actually need one? Cariad and Catrin confront the dysfunction of their relationship past and present and the division that an unsuspecting visitor brings. On the day of their late mother's 50th birthday, the sisters are burdened by the notion of commemoration. Catrin's got an eleven o'clock lecture and Cariad's got 500 words to write. They've got their hands full with one guest, let alone two. Her unveils the complexities of familial relationships and of sexual, romantic pursuit.