Charlotte and Colbourne rush to Augusta’s aid. Tom secures a financial investment… but is delivered some devastating news. And while love blossoms elsewhere, Arthur’s heart is broken.

Nancy oversees a child born out of wedlock, but things take a very unexpected and shocking turn. Dr. Turner and Sister Veronica discuss a new contraception procedure: the Vasectomy. The Board of Health delivers some unwelcome news to Sister Julienne.

Charlotte attempts to distance herself from Colbourne but as they are repeatedly thrown into each other’s orbit, their chemistry rises. Meanwhile Georgiana is unravelling and makes a surprising decision to protect herself.

Nurse Crane is shocked when her fitness comes into question during a ventouse training course. Trixie cares for a Hindu mother and her newborn twins, but it’s not long before an emergency gastroenteritis outbreak is declared at the maternity home.

Georgiana gets a surprise visit. Colbourne’s shooting party goes ahead and Charlotte has to confront all that she’s lost. Mary and Tom cross swords over his plans for the old town.

As she sets about helping a mother whose newborn baby is suffering from a clotting disorder, Nancy is harboring a secret of her own. Sister Veronica meets a newlywed on her rounds, and the case shocks the women of Nonnatus house.

Georgiana faces a nearly impossible task in trying to find a lawyer, but help arrives from a surprising place. Lady Denham accepts a new vision for the town and spars with an old flame. Arthur makes a new friend.

Lucille struggles with her mental and emotional health; Sister Julienne is deeply concerned by an angry red rash on a patient’s breast and a referral is quickly made to St Cuthbert’s.

After confessing her true identity to an angry Johnny, Ellie unsuccessfully tries to persuade a police inspector that Frances's and Greg's deaths were linked. Drunk and abusive, Frances's husband David turns up and admits to an affair with Milena to spite his wife's infidelity. Obtaining the truth behind the murders puts Ellie into danger.

Ellie goes to Milena's workplace using a fake name under the guise of being helpful – but really looking for clues as how Milena knew Greg. Milena's business partner, Frances Shaw, confides in Ellie that her own marriage is over, as she had fallen for Milena's lover. But Ellie does not get the chance to find out the name of Frances’ lover.