Gemma Hayden has returned to her hometown of Alice Springs for a new job as a primary school teacher. It's been six years since her family broke apart following the disappearance of her twin brother. And the scars still run deep.

Hard on the heels of her homecoming, Saul Pearce, the man she once loved, is reposted from Parks and Wildlife in Darwin back to Alice. When an old car wreck is uncovered, washed down the river to Ruby Gap, Saul investigates only to find that the wreck belonged to Ethan, Gemma's twin - and there's a coded note for her in the glovebox.

Joining forces, they trek through the rugged outback, piecing together clues that not only bring them to the attention of a criminal organisation, but lead them to uncover an even older puzzle ... One now lost to the history books.

With targets on their backs, will they unearth the truth in time?