Hotch receives a telephone call from his estranged New York based brother Sean, who he has not heard from in four years and coincidentally while Hotch and Jack are in New York visiting Beth. Now working as a bartender in a club, Sean wants Hotch's help in a death that occurred in the club, where the woman in question quickly bled out through her eyes, mouth and nose just before her death. Hotch convinces the team that this death is the basis for a case when Sean tells him that his own girlfriend also recently died the same way. The team quickly learns that these two deaths are not the only ones, most to hit drug users in clubs. But what confounds the team is that a few victims, such as Sean's girlfriend, were non-drug users. The drug found in each of the victim's systems was Ecstasy. They later learn that the form of the drug that killed the victims was a more lethal variety that has not yet been known to have hit the US. They have to find the source of the drug and how it was administered to such a diverse group of people to find the unsub. They believe the focus of the case is the Edinburgh, the club where Sean works. As such, Sean and his colleagues are considered suspects. Through it all, Hotch examines his relationship to Sean and how their lives have diverged when they were children, when Hotch was considered the troubled child and Sean the good one.