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 hashuged 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.

David Sandstrom searches for a drug cocktail to save Audrey Graves, a pregnant woman who has been infected with a new strain of HIV from Africa. In an effort to save her baby, Audrey is induced at just 26 weeks; but it is too late, she has progressed to full blown AIDS and her baby has been exposed to the virus. Carlos attempts to trace the new strain of HIV back to Patient Zero and he encounters many painful memories of his own time in Africa.

Meanwhile, Mayko recruits Simon Jessup, a British neuroscientist, to help her investigate a possible link between IQ spikes and Mad Cow disease. Mayko and Simon begin to develop a personal relationship.

David has less than two days to discover a drug cocktail that will prevent a premature baby from becoming HIV positive. After he discovers a mixture that will save the baby, he encounters a number of bureaucratic roadblocks because the drug has not been approved.

Carlos continues to research the new super strain of HIV with former colleagues in Africa, and realizes that his place is at NorBAC.

Mayko and Simon's investigation of dramatic IQ spikes in children who have been exposed to prion-laced chicken takes them to the United States. They make a brilliant finding but the results are devastating. Meanwhile, Mayko is troubled by some news she discovers about Simon.

While attending a conference in New York, David chases Owen a petty thief into the city's abandoned subway tunnels where he finds an underground community of homeless people. David discovers that some of the inhabitants share symptoms of a mysterious illness and he begins to investigate.

Back at NorBAC, Jill believes that she has discovered a cure for juvenile diabetes from an unsanctioned line of stem cells.

Caroline's nephew Glenn who has been lying in a coma is beginning to show some signs of response.

Jill's potential cure for juvenile diabetes is compromised, causing protestors to demonstrate outside NorBAC. To further complicate matters, Jill discovers that the stem cells she used may be infected with a retrovirus; the implications of which would be felt the world over.

Carlos and Mayko continue to test two critically-ill, homeless people David found living in New York's subway tunnels. Their symptoms can't be linked to any known disorder; however, they may be connected to an underground marijuana grow-op.

Meanwhile, NorBAC is briefed on a strike by the U.S. Government on Cuban labs that may be responsible for the devastation of 1500 acres of orange groves in Florida.

David gets devastating news from his father in Vancouver.

While dealing with his mother's recent passing in British Columbia, David is asked to travel to Florida and Cuba with Carlos. NorBAC has been asked to investigate the claim of exiled Cuban millionaire Salvador Charringa, that his Florida orange groves have been destroyed by a biologically engineered bacterium known as x fastidiosa. When it starts to look like every major institute in Cuba is clean, David speculates that Charringa and the White House are trying to start a conspiracy to justify the invasion of Cuba. Just as tensions between the U.S. and Cuba are about to come to a head, David and Carlos, with the help of Cuban scientist Eva Ramone, discover exactly what the White House and Charringa have been looking for.

Believing that Glenn is beginning to emerge from his coma, Bob enlists the help of neuroscientist Simon Jessup to determine a prognosis.

While in Cuba investigating the cause of decimated orange groves in Florida, David and Carlos uncover information that points to a possible bio-terrorist plot on the part of the Cubans. The American President jumps theballoon and immediately blames Cuba for the damaged crops.

In her search for a cure for Juvenile Diabetes, Jill confirms that the Korean stem cell line is contaminated with a virus. Before her ground-breaking results can move forward, she must prove that the virus is harmless.

Caroline's nephew Glenn fails to respond to his surgery, but does manage one last devastating message.

Bob's attention turns to the escalating danger in the skies over Mexico city, where a massive brown cloud has begun to combine with the toxic emissions from a nearby volcano. The new mixture could rain sulfuric acid down on the city and Bob must try to convince the Mexican officials of the gravity of the situation before all of Mexico City is destroyed.

Homeland Security is monitoring two scientists in Chicago who they believe are a threat to the US President. After taking samples from their lab, David feels the investigation is unwarranted and the two are set free.

Owen shows up at David's office looking for a place to stay.

NorBAC's investigation into a cluster of sleepings occurring in the southern United States uncovers an unnatural enzyme in the brains of the victims. They are receiving something from their environment, and it's causing sudden and severe depression, but where is the enzyme coming from?

Meanwhile, the wife of a longtime scientist-friend of David who washuged in a car accident asks David to decipher the secret project her husband had been working on. With the help of Bob and Carlos, David discovers that his friend was genetically engineering mice. They soon deduce that he had discovered the gene that causes homosexuality and had initiated a patent for a drug that would suppress the gene!

Bob scrambles to neutralize the Asian Brown Cloud before it dumps a deadly shower of sulfuric acid on Mexico City.

Owen shows up at David's apartment after Jill encounters him stoned on crystal meth but David decides to give him one more chance to clean up his act.

Autopsies on two dead deer lead NorBAC to suspect that worms from parasitic eggs are responsible for a recent spike in depression-related sleepings in the Southern U.S. What they can't figure out is if the parasites are coming from the deer, humans or a third source.

While working on a retrovirus, Jill becomes contaminated and is forced into quarantine.

Owen is charged with criminal negligence when a young girl dies after overdosing on crystal meth. David comes to his defense, arguing that Owen is predisposed to being an addict. The defense sparks a fascinating legal, scientific, and ethical argument.

NorBAC must unravel a genetic mystery when fish bred in an East Coast fish farm start exhibiting unexpected and dangerous mutations. Furthermore, a number of kids in an East Coast village are becoming ill; could deadly radiation be leaking into the Ocean?

The team continues to work on a promising anti-parasitic drug after a spike in Arkansas' sleeping rates is traced to worms brought into the state on the winds of hurricane Katrina.

Caroline is in Washington being briefed about a new looming crisis - an entire National Guard unit has fallen unconscious and can't be woken up. The illness resembles encephalitis lethargica, but the patients aren't responding to usual treatments. The U.S. military suspects the illness is the work of a radical Muslim group.

Meanwhile, Jill is released from quarantine and quickly sent home to rest.

NorBAC uses innovative scientific methods to track the source of mutating radiation that is affecting fish on the East Coast of Canada to radioactive fuel rods that were dumped into the Ocean in the 1950's. The environmental fall out could be catastrophic.

Jill is rushed to the hospital, where doctors struggle to save her life. Meanwhile, National Guardsmen in the U.S. continue to deteriorate. To David's surprise, Jill's symptoms match those of the soldiers. How could the retrovirus Jill found in her stem cells have also infected the soldiers? The U.S. military may have the answer in an untested antidote, but refuse to release it in time to save Jill's life. Once again David is forced to ignore protocol by administering Jill with the untested antidote.

David contemplates a radical experiment on his father who is in the early stages of Alzheimer's.

Jill and the U.S. National Guardsmen begin to recover after receiving the lethargica antidote; but shortly thereafter, the Guardsmen begin to fall ill again with a secondary more deadly infection. Some Guardsmen begin to die and everyone fears for Jill's life.

Caroline believes that her superiors aren't telling her everything about the lethargica outbreak and suspects that Wes, her executive assistant might also be in on it.

Out of nowhere, the Manford brothers show up at David's apartment and shed some light onto the recent epidemic.

As Caroline continues to dig, she gets dangerously close to unearthing a conspiracy that could go deep into the White House.