It's May 22nd, 1968, deep in the Atlantic Ocean 400 miles southwest of the Azores.

Francis Slattery, captain of the USS Scorpion, a nuclear-powered submarine, looks across the busy control center.

Captain Slattery is 36 years old and a rising star in the United States Navy.

He's trained for years to lead submarines like this into battle, but he's not taking the scorpion to war today.

He's taking his ship home.

The scorpion glides through the waters a few hundred feet

below the surface, heading west toward America at a speed of 18 knots. The submarine hums with

quiet and efficient activity that pleases slattery. He's been captain of the submarine for less than a

year, but knows every inch of his command. He can picture the ship's cooks busy in the galley,

the engineers who are hard at work in the engine room,

and he knows that three decks below the control center,

a routine battery charge is underway.

Captain Slattery decides it's time to come up to periscope depth.

He gives the order, the submarine pitches upwards,

and the words, set-conditioned baker throughout the ship echo along the scorpion's compartments.

In response to Captain Slattery's order, the crewman seal the scorpion's watertight doors.

This is standard procedure.

Periscope depth is potentially hazardous for a submarine, as it's not always possible to detect obstacles near the

surface. So Conditioned Baker is the order given to prepare the ship for any eventuality.

But neither Captain Slattery nor anyone else on board is prepared for what happens next.

The scorpion shutters as an enormous explosion shakes the boat.

In the confined space of the submarine's reinforced halt,

...