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.

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.

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.

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.

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.

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 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.

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.

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.

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.

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.

What happened to Bob, Mayko, David, Jill and Caroline? 6 months after the explosion, NorBac is still rebuilding itself. The team has to deal with the deaths of several of their friends and colleagues and the arrivals of new people for the team.

NorBac must find a cure to a bacterium that will surely kill David and Bob if they do not succeed. They also need to engineer the cure so that it eradicates the bacterium that was probably transported by the wind after the explosion of the lab in Utah.

The team traces the Sinatra virus to an organ donor in the Philippines; David blames himself for allowing Owen to try experimental gene therapy to cure his drug addiction.

Several fires in British Columbia start. One of the action organizers calls NorBac in as several firefighters present strange symptoms. Craig, Rachel's son, come visit her mother at NorBac. Both Mayko and Carlos are attracted to him.

David discovers that NorBac has been tapped by Riddlemeyer. The team must find what caused the bear to attack Craig with no reason as a human being is presenting the same symptom. To save Bob's eyesight, David decide on a peculiar procedure.

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.

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.

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.

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.

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.

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.

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.

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.

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.