Someone from Derek and Addison's past arrives in Seattle and shakes things up. Meanwhile, Burke learns about Christina's secret and, after a visit with her mother, Meredith looks into more of her family's dirty laundry.
An assassination attempt on President Bartlet leaves some of his team fighting for their lives, and a crisis in Iraq requires immediate action.
On Christmas Eve, Josh meets representatives from the American Trauma Victims Association, and the events of the three previous weeks are recounted.
The President's life becomes a nightmare when India invades Kashmir, and his daughter wants to date Charlie. Meanwhile, Leo's drug troubles escalate.
When the decaying corpse of the Venezuelan Ambassador’s son is found hanging from a tree on the campus of an exclusive private school, Dr. Temperance Brennan and Agent Seeley Booth are called in to investigate. The cause of death seems to be suicide, but both Brennan and Booth suspect there may be an alternative cause of death.
