Don and his team are called when it is discovered that a truck driver and his big rig carrying radioactive material have been hijacked and are now missing. They are pressed for time to find the truck when the hijackers threaten to detonate a dirty bomb in an undisclosed location in Los Angeles if they don't receive $20 million in 12 hours.

When a UFO is spotted dangerously close to Los Angeles, Don recruits Charlie to help locate the mysterious aircraft's point of origin and is surprised when it turns into a murder investigation.