The Enemy Within - Season 1 Episode 4 -

When intelligence obtained by Shepherd during her stint at the notorious ADMAX prison is linked to a pending attack on U.S. soil, Keaton and the Cointel team embark on a manhunt to find and stop a deadly international operative. Keaton confronts questions of loyalty and betrayal when it comes to Anna Cruz and his late fiancée's father, Thomas Heffron.