A tremor on Rock Island beach uncovers a mysterious portal to the lost civilisation of Atlantis! Unfortunately, Raquel finds the portal before our gang and matters are complicated by the arrival of a mysterious girl who asks out Ellis on a date.

Taylor and her friends must save the island from an ancient piece of glass that is wiping everyone's memories. But will they even be able to remember there is an island to save? And more importantly, will they remember Lila's birthday?

When teenage versions of Taylor's mum and her Uncle Charlie materialise at Taylor's house, the gang must figure out how to reverse the phenomenon before their timeline is interrupted and Taylor ceases to exist.