HMS Turbulent makes its way toward the troubled waters of the Middle East, becoming the first British submarine to pass through the Suez Canal since the Egyptian revolution, a nervous moment for all concerned. Arriving at the Bab el Mendeb Strait between Somalia and Yemen, Captain Ryan Ramsey and his crew have to conduct anti-piracy operations throughout the night. At the same time, there are new recruits to be trained for action, while Richard and Timmo both find themselves at a turning point in their careers.