Technological advances have escalated Cold War tensions to an all-time high, and undercover KGB operatives Elizabeth and Philip Jennings face the growing threat of discovery. As their assignments grow more deadly, their family is in more danger, and their loyalties are tested like never before.

John Jasper is haunted and restless. Unhappily settled as choirmaster in the provincial cathedral town of Cloisterham, Jasper finds himself striving for the divine in his music even as he struggles against madness brought on by ennui and opiates. Aware of his unraveling, Jasper believes his salvation may be found in the arms of Rosa, his prized pupil. His only obstacle is her fiance, Edwin Drood - Jasper's nephew.

The stakes have never been higher for KGB operatives Philip and Elizabeth Jennings than in this pulse pounding fourth season. Still grieving the death of her mother, Elizabeth berates Paige for telling her pastor about her parents' covert profession. A deadly bioweapon threatens Gabriel's life, and the couple shatters the lives of loved ones when Martha is told Clark's true identity and Elizabeth betrays her friend Young-Hee.

Philip and Elizabeth find themselves at odds over their daughter's future now that the KGB is determined to recruit her. FBI agent Stan Beeman rededicates himself to uncovering the identities of the Russian spies.

With her dad in the hospital, Bea finds herself staying at her grandmother's apartment the same way she did the summer before her mother died. As she avoids her fears about the situation, she discovers she can see imaginary friends, and they enlist her to help them get reassigned to new children after their people have grown up and moved on, thinking they no longer need their old emotional supports. The more she tries, the more she realizes that the...