Kelly Green and her sister Kayla grew up summering on a small island off the coast of Northern California. After Kayla's death, Kelly returns to the island where she joins three friends from her past, to commemorate both, Kayla's life, and the life of a sixteen year old girl who disappeared from the island twenty five years earlier. Now in their early forties, each of the four remaining friends struggle to find a way to deal with their loss while also dealing with their own personal crisis. Meanwhile, the new sheriff on the island, also a childhood friend, seems to have stumbled onto an interesting pattern the previous sheriff overlooked all together. Apparently a sixteen year old girl has gone missing from the island every fifth summer since Peggy disappeared. Some were assumed to have run away, while others were reported as missing, but one thing is for certain, none of the girls were ever seen again. As the sheriff, the women, and other friends from the past, work together to piece together the random clues they hope will provide a mirror to the past, disturbing evidence begins to surface suggesting that the next girl to disappear will disappear this summer.