According to her own moral calculations, Katie Carr has earned her affair. She's a doctor, and doctors are decent people, and her husband David is the Angriest ... » 

According to her own moral calculations, Katie Carr has earned her affair. She's a doctor, and doctors are decent people, and her husband David is the Angriest Man in Holloway. When David suddenly becomes good, Katie's sums no longer add up, and she is forced to ask herself some questions. «