The agency is trying to find out the if the creator of the super virus is guilty because several people have died to the virus having thought to been sold. Stiles travels to Mexico City to see if the scientist is guilty. Stiles needs to find out where the virus is made, Stiles who came to Mexico begins to believe the scientist is innocent.

Stiles enters the lab and finds a lot of empty vials. Gage finds out that scientist's records list 75 vials as well as 73 in the lab that don't contain the virus. They believe one of the scientist family members has the vial with the virus. Haisley learns that Stiles and Teri may have the wrong man.

Stiles learns the scientist may have been making a vaccine for the virus.