A German submarine hunts allied ships during the Second World War, but it soon becomes the hunted. The crew tries to survive below the surface, while stretching both the boat and themselves to their limits.

A deadly airborne virus finds its way into the USA and starts killing off people at an epidemic rate. Col. Sam Daniels' job is to stop the virus spreading from a small town, which must be quarantined, and to prevent an over reaction by the White House.