A personal tragedy reopens old wounds for the Mullen family. Speaker Dreyer pushes for a change in leadership. Sheila testifies before Congress.

A new threat creates further unrest across the nation. As he narrows in on the culprit, Mullen is faced with an agonizing decision.

A shock to the financial system increases scrutiny on Mullen's commission. Valerie investigates Proteus. Roger must make a difficult choice.

Former President George Mullen's comfortable retirement is upended after he's asked to lead an investigation into a horrific cyberattack.

Mullen's initial arrests draw blowback from the public — especially TV pundit Evan Green. Alex faces pressure to investigate her father.

Mullen's commission investigates a hacking ring. President Mitchell weighs retaliation. A powerful figure has demands for Roger.