Grace realises that something is up with Kitty as she keeps her distance. A Major wakes up from the verge of death, still badly wounded he also has to find out that his troops have been decimated. The hospital prepares itself for a convoy of new patients.

Paranoia is rife as the hospital anticipates the court martial of a patient. Thomas's pioneering system brings him into conflict with a senior officer.

A band of patients known as the Lucky 13 lift spirits in the hospital but one holds a secret which could threaten their safety. The return of a patient spells trouble for Margaret.

A hostile patient forms a connection with Grace as she recalls her time in India, and Joan risks everything as she awaits a response from her fiancé.

The hospital is thrown into disarray as Joan faces a charge of aiding the enemy.