It's May Day and the members of a small community go about their business as they wait for this year's parade to begin. But when the May Queen - local teenager Hattie Sutton - fails to appear, several townsfolk are sent spinning by the suspicion that someone among them has taken her.

A devastating discovery throws the spotlight on a key suspect and forces Gail to face unwelcome facts about husband Malcolm. Caitlin and Linus's relationship deepens when she tells him a shameful secret about the day her sister went missing, while Fiona grows suspicious of Everett.

The day after Hattie's disappearance the locals unite to look for her, with Steve leading the search in the hope of winning favour with the girl's family, and also to conceal his worries about his brother. Routine questioning by the police gives Linus food for thought about his father, while Gail grows increasingly suspicious of husband Malcolm, so her son James goes rooting through his office for clues. Ex-cop Fiona ignores husband Alan's protests and embarks on her own unofficial investigation.

Linus makes a dangerous promise to Caitlin and discovers the true nature of Everett's connection to Hattie. Fiona and Alan come to blows over Charlotte's odd behaviour, while Gail's lack of forgiveness drives a wedge between her and James.

As the townsfolk gather for the memorial, things take a dark turn and a chaotic interruption has fatal consequences. Steve finally gets his moment with Angie - will he manage to win his family back? Fiona must face her old colleagues in a way she never thought she would, Caitlin makes an eerie transformation, and Everett and Linus have a confrontation that takes their relationship to a new level.