Nikt nie wie, co się stało z Bobem, Mayko, Davidem, Jill i Caroline. Pół roku po eksplozji NorBac próbuje podnieść się z popiołów. Zespół musi dojść do siebie po śmierci współpracowników.

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 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 rozwiązuje zagadkę syndromu Sinatry. Owen próbuje popełnić samobójstwo. Pojawiają się kolejne przypadki zabójczego wirusa. Agenci NorBAC robią wszystko, aby odnaleźć Pacjenta Zero.

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.

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.

NorBAC prowadzi śledztwo w sprawie agentów biologicznych. Syn Rachel i Carltona, Craig, zostaje zaatakowany przez wściekłego niedźwiedzia. Bob ma nadzieję na poprawę wzroku.

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.

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.

Okazuje się, że Carlos mógł zarazić się krymsko-kongijską gorączką krwotoczną. Po eksperymentalnej operacji Bob staje się wyjątkowo wrażliwy na emocje innych. Carlton może mieć kłopoty.

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.