It's a busy night at the Maternity Home, all the beds are full. One of the mothers is Shirley Dent, who runs into her old friend, Marion Smith, who's also ready to give birth. Shirley is excited to see Marion, but Marion is cool to her. Later, both women give birth to baby girls.
At the Turner House, Timmy is developing pictures. He has a new love: photography, but he's been using a simple camera. His father sees the pictures and is impressed, so at breakfast he gives him his old camera.
Fred and Violet are walking home from their civil defense meeting. The two are talking and flirting, and as Fred leaves he gives a little excited dance-kick.
The next morning, Sister Evangelina is tending to the Smith and Dent babies when there is an explosion. Shelagh runs out and says there's a fire in the laundry room. Evangelina scoops up the babies and takes them outside to safety. The mothers emerge, and she gives each one of them their baby, or so she thinks.
Meanwhile, Cynthia is at the home of Gert and Tommy Smith. Tommy is an invalid and Cynthia is tending to his bed sores. Gert is washing his sheets in the living room, and it's obviously a great effort. Barbara arrives. She's been tasked with selling the free laundry service to the local incontinents. Gert refuses the service, saying her husband would be embarrassed by it.
Back at Nonnatus House, Barbara talks about the Mills and how she wishes they would take the service. She finds out the Mr. Mills is a relative of Fred's and wonders if he can help convince them.
Patsy and Delia Busby are in a cafe. Patsy is sharing with Delia about the fire. Delia tells Patsy she doesn't know what she'd do if she lost her, and Patsy says she's the same. The two commiserate about the fact that they can never be together, and Delia says maybe it would be easier if they would each just find men to marry and settle down and have done with it. They're interrupted by a man hitting on them, and Delia storms out.
Patsy follows and asks Delia if she was serious about wanting to get married. Delia says she is ... she wants to marry Patsy.
Later, Patsy and Sister Monica Joan are putting up a flyer about a Halloween turnip parade for the children. Monica Joan goes on about how this will bring up the spirits of the undead, which draws the interest of a young girl names Glenda Severs, who wants to see her mother again. Monica Joan says she's not in charge of the spirits, but doesn't actually tell the girl no.
Fred tells Violet that he feels guilty for not visiting his uncle, Tommy Mills, and Violet resolves to go with him. Fred is touched by the obvious love the Mills have for each other. As they are leaving, Violet sees Mrs. Mills changing a dressing on her own chest. There is an open wound there. Gert asks Violet not to say anything about it, but Violet tells Doc Turner and Barbara about it.
Fred and Violet are having a conversation, and Violet is reminiscing about her dead husband. Fred feels awkward about this, which Violet calls him on. She tells him either he likes her or he doesn't. Fred mumbles something and walks out.
Sister Evangelina visits the Smiths and their baby, and sees baby Debra's lips are a little blue. She gets Doc Turner, who says the baby likely has a heart murmur and needs to be sent to the hospital right away.
Later, at the hospital, Evangelina visits Marion Smith as she looks from afar at her baby. Marion tells Evangelina that she'll be alright because she has "the angel's kiss," a birth mark on her leg.
Timothy Turner is developing film from his dad's old camera when he comes across a photo of himself as a toddler in between his dad and his mom.
Back at Nonnatus House, Evangelina and Trixie are sitting by the phone, when Trixie mentions that the Dent baby had a birthmark on its leg that seems to have faded now. Evangelina starts freaking out, and realizes that the babies got switched during the fire. She tells Sister Julienne, and along with Shelagh they look at blood records and find out that the switch did indeed happen. Evangelina is inconsolable about this mistake, and blames herself.
Barbara and Gert Mills visit the doctor, who tells her she has breast cancer. He wants to perform radical mastectomy. Gert's main concern is for her husband. She doesn't know who'll care for him while she has the surgery yet at the same time is afraid of dying and leaving him alone.
Glenda returns to talk to Monica Joan, and gives her a letter she's written to her dead mother. Once she leaves, Fred tells Monica Joan that Glenda's mother isn't dead, that she ran off on her when she was just a few months old.
Sister Julienne and Sister Evangelina break the news to the Dent and Smith parents that their babies have been switched. The do not take it well. Marion Smith tells them that Shirley Dent is not capable of tending to a child with a heart condition.
Sister Winifred goes to visit Mr. Severs to get the whole story about Glenda's mother. He tells her that his wife cheated on him and ran off, and that though he loves her like she's his own, he's not even Glenda's biological father. Winifred tells him about the issues Glenda seems to be having.
Later at home, Mr. Smith tells his wife that maybe they got lucky, and will get a healthy child and not have to deal with the heart condition after all. Marion is not hearing it.
Making sure that Cynthia will take care of her husband while she's gone, Mrs. Mills agrees to have the mastectomy.
At the Halloween turnip parade, Glenda Severs has not found her mother. Her father comes instead, and tells her that her mother asked him to look after her. This seems to make her feel a little better.
Fred visits Violet and apologizes for walking out on her. She tells him she's closing shop and moving to Plymouth with her son, because there seems to be nothing for her in Poplar. Fred proposes, and she accepts.
At the turnip parade, Patsy finds Delia. She tells her that neither of them is dead yet, and somehow they'll find a way to be together.
At the hospital, Shirley brings her baby to Marion, and the two both look at Debra. Shirley convinces Marion that she can indeed look after a child with a heart defect, and reluctantly and not without tears, the two agree to switch the babies back.
Some time later, Gert Mills, having had the mastectomy, returns to her husband, and the two prepare to have much more time together.
Sister Evangelina is still pretty upset about the baby mix-up. Sister Julienne come in to comfort her and says "We go forward, Sister. Together. As a family."
Chad Grayson has been a gas station attendant, sold video games over the phone, and even was the person who cuts the mold off the cheese in the cheese factory, but spent most of his career as a middle school Language Arts and History teacher. He is now a full-time stay at home dad and writer. You can find him on twitter at @chadgrayson and on his blog at cegrayson.wordpress.com.