Teenagers Corey Alloway and Bree Dovemuir are best friends. They live on an island where people still pray to ancient Greek gods and the Underworld is rumoured to be visible from the top of a certain hill. They're closer than sisters - until Bree betrays Corey and steals her boyfriend Ali. Corey is consumed by hatred. She goes so far as to vehemently wish Bree dead. At the annual Thesmophoria Festival Corey kisses a stranger a boy with golden lips to show Bree and Ali she's over them both. And later that night Bree is found floating in the lake - dead . . .