Ross Kemp continues his adventure in Scapa Flow, Orkney, heading out again with local expert dive guide Emily Turton and dive supervisor Neil Brock. Plunging down on the wreck of German warship, SMS Karlsruhe, he discovers why the German WWI warship ended up and the bottom, despite coming to the Royal Navy base in peace. The answer leads him 600 miles to explore the wreck of on an experimental 1920s submarine aircraft carrier called the M2. His dive unravels the tragic truth about how it was lost with all hands in 1932.