On the shores of Cape Mercy, a skillful group of teen divers investigate a series of secrets and signs after one of their own mysteriously goes missing.

While the town searches for Lauren, Dive Club begins their own investigation. Izzie finds Lauren's phone, which contains a hidden message suggesting her disappearance was no accident.

The girls break into Lauren's house looking for more information and find an old coin belonging to Hayden. Izzie finds a diamond brooch in Lauren's wetsuit.

Dive Club discovers that Hayden's coin has some significance and that Lauren was communicating with a mysterious person named LK

It's the day of the cabaret fundraiser and Dive Club discover who the mysterious LK is.

With the town of Cape Mercy believing Lauren is dead following the discovery of her sailing jacket, a memorial is held in her honor.

Dive Club and Leonid dive the dangerous Russian shipwreck causing dire consequences.

Dive Club learns the significance of Hayden's coin, which takes them on another wreck dive.

Viktorya shares a family secret with Anna. Hayden tells Henry he's found a way to pay off his debts. Izzie steps up her relationship with Henry and Maddie finds a painting that changes everything.

The Salvation Day celebrations begin, and the town is in good spirits. All that changes when a SOS flashes out from the lighthouse. Is it Lauren?

The truth is pieced together as one of the girls is forced to choose between friends and family.