The game takes place in 1937. Germany won WWI and conquered Britain. They captured three of the four Admiral (Hood) class battle cruisers while the rest of the Royal Navy, along with Churchill, fled to Canada and the rest of the empire. The Royal Navy in Exile (RNE) is allied with Japan as the "League of Free Nations". The RNE is also ticked at the U.S. because we didn't help them in WWI. Japan has not become the militarist country it was following WWI. The Germans are threatening to invade Ireland which the U.S. has a defense treaty with.
The single player missions takes one through the quasi-naval war that is occurring between the various sides. You can play as a surface warship, Corvette, DE, and DD, or a submarine. (The update that is available lets one play a mission as either the Hood or its German counterpart.)
I won't spoil the ending but lets just say the world erupts into another global war. That is where the multiplayer is suppose to begin.
It's out, but it's not MMOG. It's fun but it could have been better.