Welcome aboard The Sacramentum. New recruit Jamie Walsh gets a crash course on ship life while trying to keep a low profile as he investigates what happened to his missing sister.

After shocking news concerning a chief suspect, Jamie and new friend Vivian work together to discover the identity of an officer onboard who was connected to his sister.

It's a big day on the ship - the captain's ball, attended by the VIP guests. Jamie shares an intimate moment with Olly, while Vivian cosies up to Lily, one of the guests, risking big repercussions if she's caught.

Jamie gains an unexpected ally on board, who promises to investigate from the inside and get the answers he's desperate for.

While Vivian and Lily's relationship reaches new heights, Jamie finds himself in a terrifying situation and must use all his courage and strength to escape.

Jamie finds himself in a lethal dead end with seemingly no way out. But after a surprise intervention brings some momentary respite, he learns that others are in peril.