Abu Nazir kidnaps Carrie, and uses her as leverage to get something from Brody.  He asks Brody to get a number from Vice President's office.  That number allows Nazir to manipulate Walden's pace maker.  Once Brody knows that Carrie has been let go, and is safe, he gives Nazir the number.  Nazir's man gets to work immediately; Walden goes into cardiac arrest, and flat lines.  Carrie then makes her way back to the building Nazir was holding her in.

Meanwhile, Saul continues to question what Quinn is doing.  He asks Estes about, who quickly tells Quinn that Saul "knows."  When Saul attempts to leave the building to help on the operation, he is detained.