The USS Nathan James carries to virologists. Unknown to the crew at the time, they are collecting samples of a deadly virus tht has wiped out over half of Earth's population.

Virologist Dr. Rachel Scott lands in Egypt at the latest outbreak of "the virus." Once the spots come, the infected die within two days.

The USS Nathan James is preparing to set off and Admiral Halsey, a German Shepherd is one of the unusual passengers. Commander Chandler welcomes Rachel Scott onto his vessel. Seeing the hazmat gear, Chandler asks if he should be concerned for his crew. They assure him the gear is only to keep from contaminating their work.

Four months later, a Nathan James top secret Delta Mission introduces us to XO Mike Slattery in the arctic, wishing he had taken a job someplace warm.

Chandler announces all tests were completed successfully and they're going home. He's going to arrange for phone calls and messages they can send to their family.

Lts. Danny and Kara are having an affair. They'll likely be the lucky ones.

Chandler learns their mission has been extended and they are to maintain radio silence until further instructions arrive.

Helicopters are engaging the soldiers protecting the virologists on the snow with rapid firing. The sailors take one copter down and another is fired at, causing two men to drop out for man to man gunfire.

Admiral Healy saves Rachel by attacking one of the gunmen. Their orders are to take them alive. The guy says he wants the cure.

Chandler threatens to toss her work overboard unless he gets answers. Rachel informs him about the virus. When they left Norfolk, they were at phase two. Now they're at phase six -- 80% of the world's population is infected.

The speaker of the house is now the president of the United States. They have no allies and no enemies, just a lot of unfortunate people. If Dr. Scott has the makings of a cure, she has to come home. Now.

The crew tries to come to terms with the fact they'll likely never see their families again. Four people on board got through to anyone and the news wasn't good.

Slattery got through. His boy is gone and his wife and daughters are in a safe zone.

Incoming missile! It's a nuclear missile that overshot and is heading for land. A nuclear detonation can be seen in the distance. They're thrust into darkness on the USS Nathan James. The virologists could lose everything.

There is a cloud of radiation ready to drop on them and they have one fuse left.

An Italian ship is spotted. No communication. They need to go to the ship for fuel and food. The ship has been infected and the virus is airborne. They open the freezer for meat and find bodies instead.

One of the sailors falls down the stairs after tripping over a body. His mask falls off. He blisters immediately and takes his own life rather than die of the virus.

The virus has an extra gene now. It was possibly weaponized or escaped from a lab. The good news is the virus has stabilized and should be easier to contain with a vaccine. Rachel has the primordial sample and that's why she can create it.

A video message from Chandler's wife, Darien, got through to him and she and his kids are safe, having escaped months earlier to a remote location.

Chandler decides to ignore the 5-day old message from the POTUS to go home create the vaccine. Seeing the news footage, no further communication and the belief that their duty is to the entire world, they stay at sea to create a vaccine.

Rachel's fellow virologist makes contact with someone, in Russian. They're turning away from America. He doesn't know what to do.