A severe blizzard causes a city-wide blackout, adding to the obstacles the team must overcome in order to solve a murder case that could be linked to a potential viral outbreak. But when Booth and Brennan find themselves trapped in an elevator during the power outage, Sweets is on hand for outside assistance, but does more than what's asked of him when he initiates a touchy conversation about Booth and Brennan's relationship. Meanwhile, Angela and Hodgins get worrisome news about the health of their unborn baby, and Hodgins and "squint" Wendell Bray get creative in the lab and put their scientific skills to use to identify the victim and the rare disease.