In the continued investigation of the "Iraq War Syndrome", David (Peter Outerbridge) checks out a theory that the water purification system has malfunctioned. In Mexico, Jill (Sarah Strange) and Carlos (Conrad Pla) make a connection between a hybrid plant designed to detect land mines and the hemophilia epidemic. When that theory fails, David joins them in Mexico and explores the possibility that mosquitoes bred to eliminate malaria might be responsible. Bob (Dmitry Chepovetsky) quits NorBAC to pursue his love of perfume creation. Caroline (Maxim Roy) receives the diagnosis she's been waiting for.

When a gunman opens fire on a local diner the FBI knows it is related to a recently arrested drug lord. However Jordan and Dr. Macy are less than convinced. After some investigating they soon realize everything is not as it seems.

A nanny confesses to a murder and an attempted murder that she claims God told her to commit. The link is that both victims lived in the same building, which was poorly constructed, and were rumored to be having an affair.

Huff's optimistic enthusiasm for this year's Christmas celebration meets its match when Beth's family, including her sick mother and competitive sister, arrive for the festivities. Izzy strains to be hospitable and good-natured, particularly when Russell comes with an unusual date, and pays one last visit to her best friend in the hospital. Byrd plays host of his own when his lost flame Gail shows up with an unexpected present.