When the lead suspects in Grissom's serial killer case are murdered, Grissom suspects an inside job.
Piper learns Leo is an Avatar, when he confesses to her, despite the objections of the other Avatars, who believe Piper should find out on her own.
When the chief investigator of a controversial report documenting corruption within the NYPD is gunned down the day before his findings are published, Mac and Stella must find the killer, launching a massive search that makes every officer listed in the report a suspect. (TV-14)