Local girls are going missing.
And the secrets lie close to home...

Following their father's death, Cass and her sister Sid will do whatever it takes to keep their family's dive school afloat.

It used to be the go-to destination in Cornwall for those keen to explore the ocean's hidden depths. But when Cass returns from a long trip, she's shocked to discover how bad things have become.

The business is in decline. Sid's new boyfriend has far too much control over the accounts - and her sister.

Then, Cass discovers a body in the water. And as more girls go missing, she wonders just how far someone will go to keep their secrets buried...