Mayday is a drama broadcast on BBC One. It’s May Day and a a tiny community is waiting for this year’s pagan parade to begin. Local teenager, Linus Newcombe, watches as the love of his life, Caitlin Sutton, kisses a rival. On the other side of town, Caitlin’s twin and the beautiful young May Queen, Hattie Sutton, is getting ready to become the town’s symbol of new life. After Hattie fails to show up, the town is sent spinning by the knowledge that someone amongst them has taken her.
The town gathers for Hattie's memorial and things end up taking a dark turn. A chaotic interruption hassome fatal consequences. Steve finally gets his moment with his ex, Angie. Fiona needs to face her old colleagues in a way she never thought she would. Everett and Linus are involved in a confrontation which takes their relationship to a new place. Caitlin makes an eerie transformation and Linus realises that he has made a huge mistake.