24 Season 5 Episode 15 Synopsis

TV Guide:

CTU follows up on information received from terrorist collaborator Collette Stenger (Stana Katic); a CTU insider becomes a suspect, and Chloe plays a key role in the investigation.

FOX:

When Jack Bauer interrogates the most recent link to terrorist mastermind Bierko, shocking secrets are revealed. Meanwhile, conflict between CTU and Homeland Security officials escalates while the terrorists threaten to boost the magnitude of their attack to incorporate hundreds of thousands of civilians.