1. Episode 1

Preparing to leave once more, huge amounts of food are loaded along with the ship's new chef, but a fire nearly undoes the entire mission right as it's begun. Northumberland is also called into action to help when a Russian spy ship is spotted.

2. Episode 2

Travelling off the coast of Scotland, Northumberland receives intelligence about a Russian submarine that's currently under surveillance. New officer recruit Olivia joins for her first taste of life at sea.

4. Episode 4

HMS Northumberland is ordered to investigate when Navy Command sends news about a gathering of Russian warships and submarines off the coast of Ireland. The timely arrival of ship's new chaplain coincides with a growing problem of decreasing morale, brought on as a result of the crew's inability to take time off. As HMS Northumberland leaves port, the chaplain tries to help the crew through another challenging mission.

5. Episode 5

HMS Northumberland is deployed off the west coast of Ireland and receives intelligence that a Russian warship has been spotted heading towards Faslane, the home of the British Trident submarine base. There is a concern that if gets too close it could pick up details of some the UK's nuclear secrets.