It's a race against time to identify the cause of a deadly virus, spreading rapidly and headed straight for the city. It's up to NorBAC to identify patient zero and contain the outbreak. As if a deadly virus wasn't enough, NorBAC's Chief Scientist, David Sandström must deal with the unexpected arrival of his belligerent teenage daughter, Lilith, and arguments with NorBAC's Executive Director Caroline Morrison over the security clearance of the one member of his team he'll need the most, his top virologist.

Lilith befriends Mick, who is dying and desperate for David to help him discover if he really is a clone and possibly save his life. Meanwhile, NorBAC has managed to locate patient zero and must proceed with the interrogations at "Hazmat City." Was this an act of Bioterrism? Caroline is determined to find out who's responsible as more die and one more is exposed. David must now face his fate.

Mick turns to Lilith, who helps him steal evidence from the scientist who cloned him, his own father. Meanwhile, Caroline suggests that Hira has possible terrorist links and shuts her out of NorBAC. David must bring Hira back. But when he does he's confronted with a rally outside NorBAC, lead by a fanatical Reverend who claims that Christ can be genetically resurrected from a Crucifixion nail. The Reverend wants him to prove it, but David's not into playing God. In the frenzy, shots are fired and someone gets hit.

NorBAC investigates an outbreak of prion disease (mad cow) in humans. The victims are spread out across North America. How are the cases connected? In the aftermath of Hiras's death, David is determined to expose the fraudulent reverend from episode 3. David suspects his old friend Danny, a hockey player, is using a dangerous performance-enhancing steroid.

David and Jill make a trip to Colorado where a rampant SARS-like outbreak is occurring. David is in shock when he discovers that the outbreak is Spanish Flu, the virus he dug up in Nunavut. Racked with guilt, he walks into the path of a car and is sent to hospital in a coma before he tells anybody his fears. Mayko Tran heads to Colorado to try to find Patient Zero.

Jill goes to Canada to see if the Spanish Flu body is still in the ground. David recovers from his coma and limps back to the office. Daisy recognises the person who created the Miranda virus and infected her baby. David identifies the vector for the Spanish Flu epidemic and tracks it with GPS.