Within 18 hours of their common time together, 12 people who visited Quiet Hills Park in Annapolis, Maryland, have died from anthrax poisoning, with at least 13 more in emergency rooms headed in the same direction. It is a highly sophisticated strain of anthrax, meaning that it was developed by someone with a science background. The military is called in as the BAU believes that such scientific work is the specialty of the military, the resulting pathogen was used as a potential WMD. Although the strain of the pathogen is not being used by the military, military scientists are the most likely candidates able to develop such a strain. The attack site, a family-oriented public park, is contrary to such work, and thus the BAU believes the site is personal to the perpetrator. Because of the panic it could cause, there is a media blackout on the story, which negatively affects some on the team, some for personal and some for professional reasons. The team is hit even harder when deep into their investigation, one of their own may have been exposed to the pathogen with just hours to live.