Rachel has difficulty adjusting to her new partner when Frank goes on an overseas attachment. Rachel and her new partner are thrown together to investigate a mysterious drowning. Constable Sam Bailey competes in a free dive competition.

Holloway and Goldie investigate an extortion racket in Chinatown. Sykes and Hawker compete against each other in an 18th skiff race.

When a man is taken by a shark in the harbour, the water police uncover a complex web of embezzlement, a faked death, underworld connections and a bizarre betrayal.

Alex's belief in the innocence of a serial arsonist leads her close to a fiery death.