In a room with no windows on the eastern coast of Africa, an Englishman, James More, is held captive by jihadist fighters.

Thousands of miles away on the Greenland Sea, Danielle Flinders prepares to dive in a submersive to the ocean floor.

In their confines they are drawn back to the Christmas of the previous year, where a chance encounter on a beach in France led to an intense and enduring romance...