As Jenny Lee begins to settle into her role as there is a new arrival at Nonnatus House. The new girl Chummy attempts to show her worth but, with a keenness to please, and her inability to ride a bike, she finds it hard to earn the respect of Sister Evangelina. Jenny sees an unfamiliar darker side of life following an encounter with a runaway.
Jenny finds her name being put on the district nursing roster for a few weeks so that she can extend her experience of community practice. She looks after Joe, an old soldier with awful leg ulcers and begins to grow very fond of him. After his condition deteriorates, Jenny realises how much their friendship has changed her life. Trixie and Cynthia enrol Winnie Lawson as a new patient.
A baby girl who was recently delivered by Jenny ends up being snatched from her pram. The local community is united as they search for the missing child. Cynthia ends up seeing another sort of loss as she soon-to-be parents David and Margaret.
Sister Monica Joan is discovered walking around near the docks and is returned to Nonnatus House by the local police. She ends up succumbing to pneumonia and after she gets better, she gets herself in trouble with the police when she is accused of theft, and all of her friends are worried that she could end up in jail. Chummy is worried after her mother makes a trip to inspect her new 'beau'.
Christmas is just around the corner and the nuns and midwives of Nonnatus House are busier than usual. After an abandoned baby is found on the steps of the convent, the whole community comes together to offer food and clothing and attempt to locate his mother. Jenny Lee ends up getting caught up in a mystery that surrounds an elderly local woman called Mrs Jenkins. Chummy attempts to pull out all the stops to stage a memorable children's nativity play.
The Nonnatus community is left feeling stunned after the Kelly family's new-born son dies in some unexplained circumstances. Cynthia, who wat the the birth, comes under intense pressure from the police, and the pregnant women of Poplar. Chummy’s decision to pursue her dream brings about a different sort of pressure ro maried life as exciting changes lie ahead for the couple.
Jenny ends up being seconded to a short-staffed London Hospital to work on the male surgical ward and finds herself working under an intimidating surgeon, Mr Tracey. The midwives have a new addition called Jane, who lends a hand in Jenny's absence.
Jenny needs to use all her skills as a midwife as she and Sister Evangelina help at the birth of the Roberts’ baby, who is born with spina bifida. Nonnatus House plays host to an friend of Chummy’s, the Reverend Applebee Thornton, who is an eccentric cleric who befriends Jane.
Crowded living conditions mean that tuberculosis has been rife in Poplar. A mass-Xray programme to diagnose the disease early though is introduced and Dr Turner is determined that the community will no longer live under the threat of the disease. The nuns and nurses attempt to support the doctor in his campaign to bring proper screening facilities to the area and Jenny’s district nursing rounds lead her to a family who have suffered devastating misfortune from the disease.
Cynthia has to administer daily insulin injections to diabetic John Lacey, a bully who consistently belittles his wife Annie. When Annie’s beloved son Bob pays a visit, Annie gains the confidence to start to turn her life around. Jenny looks after a black mother to be, Monique, who is subjected to racial prejudice from her neighbours.
The convent comes under threat as old buildings are been demolished to make room for new flats. Fred's pregnant daughter Dolly and her young son come and stay with him. Jenny is wooed by a new love interest, Alec, a friend and colleague of Jimmy's. Chummy and PC Noakes prepare for the arrival of their baby.
Trixie is upset after Jenny is promoted, but the new Acting Sister has more important things to worry about after a mother-to-be reveals that the baby she is carrying is not her husbands and that the real father is black. Cynthia decides to give a lecture on natural childbirth, believing that it will help an overly anxious patient.
Jenny ends up having an eventful couple of days, beginning with trying to help a patient who is struggling to deal with her mother, an agoraphobic who hasn't been outside for at least 12 years. Alec wants Jenny to accompany her to Brighton for the weekend, leaving her wondering if his intentions are honourable.
Sister Julienne and Cynthia are getting donated clothing ready for charity. One parcel is set to go to St Gideon's, an institution which cares for those with disabilities and learning difficulties. Jacob, who suffers with cerebral palsy, helps Sally, who has Down’s syndrome, select a pretty cardigan to wear to the institution's annual dance. Following the dance, Sally’s mother discovers her feeling unwell and takes her to Nonnatus House to be looked at. The midwives find out that she is six months pregnant, which sees some difficult decisions needing to be made.
Tom and Fred are trying to spruce up an old bus outside of Nonnactus House which waylays the midwives who are due to set off on their rounds.
Cynthia is concerned that new mother Pamela is overly anxious, when Dr Turner arrives the mother and baby can't be found. Jenny returns and is seconded to The London were she soon begins to see cracks in the establishment. Chummy visits her mother in London. Tom cancels his first date with Trixie who tries to hide how she really feels about it.
Jenny pays a home visit to first time mother Jeanette and the two hit it off immediately, she is also introduced to Jeannette's cousin Philip. Chummy discovers her mother has discharged herself from hospital and her illness isn't getting any better. After a falling out, PC Noakes finding Lady Browne in great distress brings her to the home to be cared for in her final days.
Jennifer prepares for Christmas at home with Philip, and reminisces about her friends and colleagues back in her youth. Rehearsals get underway for the Sunday School Christmas concert, as Chummy tries to choreograph the dancing snowflakes. Chummy is also enlisted alongside Patsy to run a poorly managed mother and baby home. Cynthia is drawn into a case which concerns two former residents of a Victorian mental hospital who have been left to fend for themselves.
A new nurse called Barbara, who is anxious to prove herself gets off to a bad start. A family of neglected children is discovered and Trixie becomes determined to restore their health and bring happiness into their lives.
Barbara has to deal with her most challenging case yet after she helps a first-time mother as the birth does not to go according to plan. A new nurse shows up and soon makes an impression on Sister Evangelina.
After Poplar has a mysterious outbreak of dysentery, first-time mother Marie Amos's life ends up being turned upside down after her husband Tony is arrested for gross indecency with another man. Patsy attempts to help the young couple, as Tony faces a criminal hearing. Nurse Crane attempts to help a pregnant Irish woman with two young children are covered in flea bites and clearly malnourished.
Sister Winifred learns about Poplar’s seedy underworld after she looks after Bridget Cole, an expectant prostitute. Shocked by the girl’s lack of awareness, she has to use her past teaching experience and help from SGT Noakes in an effort to promote 'safe sex' to the local working girls. Barbara finds it hard to understand why expectant father, Frank Robbins, is so desperate to have a son.
Sister Julienne is forced to question absolute faith after she meets a Christian Scientist couple who refuse medicine for their new-born child. Things become more difficult after the parents are accused of harming their child.
A secret romance ends in heartbreak after teenager Paulette Roland learns that she is pregnant. Nurse Crane helps support the couple but Paulette's life is endangered after the two youngsters go on the run.
A water shortage leaves Maternity Home is busier than ever. Two former school friends called Shirley and Marion are reunited and they are both pregnant with their first child but are now worlds apart.
Trixie and Sister Mary Cynthia work together to support a deaf mother to be, while a case of morning sickness ends up being more serious than at first suspected. Fred’s daughter is not happy about his upcoming wedding.
Christmas Day and a grieving mother receives a surprise that helps to restore the magic of Christmas.
Easter is around the corner and the nuns and midwives of Nonnatus House are as busy as ever, as babies are born to myriad families across the borough. Patsy attempts to help experienced mother Rhoda Mullucks give birth to a baby with severe deformities. After she refuses to reject her new-born child, the father finds it hard to come to terms with the harsh realities of his daughter’s problems.
A struggling dockworker’s wife has to make a difficult decision over the birth of her child, leading Barbara having to make the biggest decision of her career. Nurse Crane joins a Spanish class, where she meets widower Tommy who shares her passion for everything Mediterranean.
With modern world starting to encroach on traditional Poplar life, everybody is beginning to notice the changes. Sister Julienne is impressed by the medical advances at a local hospital that are saving the lives of mothers and babies.
Dr Turner and Shelagh campaign for better respiratory health for their patients and Timothy realises that his parents are putting themselves at risk by continuing to smoke. A back injury forces Violet to leave her beloved shop in Fred’s care and their relationship grows stronger but there are some unforeseen consequences.
Some local violent attacks on women leaves Poplar in a state of fear. Prostitute Lizzie is too ashamed of what people will think to file a report which leaves others in danger.
With Christmas just around the corner, the time has come to accept the things that have passed, and look to the future. The cause of the recent spate of infant limb deformities is finally uncovered and realising that his own prescriptions could have exacerbated the tragedy, Dr Turner is forced to jump into action in an effort to stop any further damage.