Six months after "The Millwood Massacre", the girls eagerly await a verdict in A's trial - as well as a much-needed break - until a failed exam condemns them to a fate worse than passing: summer school.

Haunted by increasingly disturbing hallucinations, Imogen attempts to forge a new identity outside of Millwood. As summer kicks off, Noa reconnects with an old friend, Tabby meets her movie-buff match, Faran gets a job as Millwood Community Pool's only female lifeguard, and Mouse is threatened by an unknown entity.

When their identities are revealed online, the PLLs scramble to figure out who is behind a series of anonymous calls - and keep Mouse's surprise birthday party under wraps. As the night of the party nears, Tabby uncovers an unsettling secret in Christian's basement, Imogen calls out her new coworker, Noa clashes with Jen, and Faran finally spills her secret.