The true story of a German-Japanese scheme to turn much of America into a radioactive wasteland.

In the early hours of June 24, 1944, U.S. Navy warplanes patrolling the Atlantic attacked a Japanese submarine known as the I-52. But this was more than the sinking of one more enemy warship. It was an event of enormous strategic importance. For the I-52’s mission was to return to Japan with the lethal ingredients of a doomsday weapon—the radiological bomb—which remained a government secret for years.

The I-52’s resting place—18,000 feet below the surface of the mid-Atlantic—became public in 1995, when discovered by ship salvager Paul Tidwell. Author Richard N. Billings has worked with Tidwell—whose attempts to salvage the I-52’s precious gold cargo continue—in bringing her secret mission to light. This is also the story of how the I-52 mission may have influenced President Truman’s decision to drop atomic bombs on Hiroshima and Nagasaki, thereby saving the United States from a similar fate.