Amid an international crisis, a career diplomat juggles her new high-profile job as ambassador to the UK and her turbulent marriage to a political star.

When a London bombing shatters her world, US diplomat Kate Wyler faces the ultimate test as her suspicions reach the top levels of the British government.

In Season Three, Ambassador Kate Wyler lives the particular nightmare that is getting what you want. She just accused Vice President Grace Penn of hatching a terrorist plot and admitted she's after the VP's job. But now the President is dead, Kate's husband Hal may have inadvertently killed him, and Grace Penn is leader of the free world. None of this slows Hal's campaign to land Kate the vice presidency. Kate steps into a role she never wanted, with a freedom she never expected, an increasingly complicated friendship with Foreign Secretary Austin Dennison, and an unnerving bond with First Gentleman Todd Penn.