After a self-imposed exile to China, David Sandström is kidnapped by the People's Liberation Army and ordered to secretly investigate a deadly outbreak that has killed 19 people in a small village. With the help of three Chinese scientists, David discovers the outbreak has been caused by an ancient bacterium that has seeped into the village's water system. David is horrified when he learns that one of the scientists has decided to test the antidote on her self in order to expedite a cure. While David makes his way back to Canada, Caroline and Carlos are witness to a horrific attack at the site of the International AIDS Conference.

Carlos and David helped by a Cuban scientist called Eva Ramone look into a claim than an exiled Cuban is a victim of bio-terrorism. Bob being persuaded that Caroline's nephew, Glenn, is improving calls Simon Jessup to help him out.

David and Carlos are still investigating the poison that is affecting Charringa's lemon crops in Florida, before the United States decide to bomb Cuba. Jill, on the other hand, asks Mayko to contact all the other labs using the same stem cells from Korea to let them know a retrovirus is in that strain. Bob offers to verify all the steps one more time with her and see if her findings are correct. Simon Jessup finding that Glenn responds to all the stimuli suggests that he undergoes brain surgery.

Bob is trying to prevent a rain of concentrated sulfuric acid that would destroy Mexico City. Homeland Security suspects two American scientists of preparing a bio-terrorist attack against the United States President and order David and Caroline to investigate.

As the investigation continues on the suicides in Arkansas, the team believes it is a chemical release by worms that is the cause. Owen is charged with criminal negligence for the death by overdose of a school girl.

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.

In order to help a mother and her unborn child, David starts a research to fight a very strong strain of the HIV virus which she has and for which there is no known cure.

The HIV strain that sean gave to Audrey Graves is so virulent that none of the new tri-therapy drugs work on it. They decide, then, to try a combination with any type of drugs that exist with the help of all the labs that accept the offer. Audrey Graves's baby is HIV positive and they hope to eradicate the virus with a new combination. Carlos is still searching for Patient Zero in Africa. In the mean time, NORBAC also looks at the devastating effects of pryon disease on humans via the consumption of infected chicken.

While in New York, David has his bag stolen. Chasing the kid who stole it, he finds himself in some subway tunnels where he discovers a young girl who is very sick.

Jill's new treatment for juvenile diabetes is halted when she discovers than the stem cells hold a retrovirus that might endanger the patients. The research on what plagues the girl found in the subway tunnel continues.

There is a series of suicides in Arkansas that Norbac is called to investigate. David tries to decipher the work of a friend who died in a car accident.

Despite David's public statement that GMO fish has no bearing on some illnesses, the dad of a young boy is convinced that his son is ill due to eating a the mutant fish. When an entire squadron of national guard falls ill, bio-terrorism is suspected, the team must work on the case.

It seems that the retrovirus that Jill discovered in the Korean stem cells is responsible for the illness affecting the national guards, thus showing the retrovirus was reactivated. Meanwhile, kids are all coming down with a mysterious and deadly disease that Norbac has to stop.

The antidote created to cure the national guards isn't doing its job properly as the guards fall even more ill with another disease. Caroline, still investigating what Weston did, finds that the White House is mixed into it.

The US government wants to cut over $3 billion out of the science budget, and NORBAC has to prove they deserve to stay in operation. Meanwhile, a West Nile like virus is breaking out in San Francisco, but it's showing some abnormal traits. A scientist at the University of Toronto claims to be able to help Owen with his addiction.

Mayko tries to get rid of the pain she's feeling in her phantom limb; the team investigates the high level of mercury contamination found in Lake McGraw.

NorBac searches for the source of a resistant strain of c. difficile; despite his limited vision, Bob proves to be an asset to the team.

Fears arise that Carlos may have been infected with Crimean Congo Hemorrhagic Fever; after experimental surgery that improves his vision, Bob becomes hypersensitive to the emotions of others; Carlton comes under scrutiny when a magnetobacteria threatens the country's electronic infrastructure.

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.

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.

A weaponized biological agent was released during fires on the west coast, NorBac must find the creator of the agent. However, Rachel is more worried about her son who was attacked by a bear.

Bob undergoes his eye surgery in the hope he won't go totally blind in the process. Carlos and David are called in in a port in Nova Scotia where a ship's crew is missing except the captain who doesn't remember the past two weeks.

NorBAC discovers a link between the tantalum contamination and the recent smallpox scam; a viral activation of dormant genes evolves Bob into a higher consciousness.

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.

As the search continues for the source of the deadly prions, NorBAC zeros in on a large agribusiness they suspect of selling infected chickens. David tries to convince Danny to stop gene therapy. Caroline insists that David interview Jill Langston, for the vacated virologist position at NorBAC. His reluctance turns to lust when he meets her.