Mo's surrogate son, William, and Sorcia arrive at Holby after an accident, testing Mo's emotional and professional abilities. Jesse shadows Sacha in a surgical role for the day.
Cara's husband's lover, Nicole, is admitted in labour, but Cara is forced to act drastically when Nicole's husband, Sean, learns he is not the father of the child.
Arthur returns to work, but his relationship with Morven is in jeopardy. Guy must overcome his lack of confidence when a young boy is admitted with a serious neurological condition.
The day arrives for Mo to return William, but she isn't prepared to let him go. Arthur is admitted with a toy soldier stuck in his arm. Sacha applies for the role of consultant, but his assessor intervenes with his treatment options.
Zosia is determined to impress Jac, but her confidence is thrown into doubt when she sees a question mark next to her name in Jac's office. Dom becomes increasingly obsessed in his patient, and struggles to focus on another patient of his.
Jac and Fran clash over a patient when Fran doubts Jac's decision to discharge a patient. Jesse treats a dying sister of a former patient of his. Rad and Fletch try to cheer Cara up.
Ric returns to Holby City, but he struggles to find his feet. Mr T makes an unexpected offer to Mo. Serena finds herself completing another Christmas shift on AAU.
Guy's career continues to strengthen and a documentary crew prepare to film him in the neurological world, but he puts a friend's life at risk in the process.
Hanssen is left with a difficult decision as Guy promises to regain control of the hospital. Jac is pitted against Guy in a fight for funding. Sacha tries to protect Essie, but things don't go to plan.
Arthur's first day back on Keller doesn't go smoothly when Morven's dad, Austin, is admitted. Mo waits to find out if she is pregnant. A shock family secret is revealed to Serena.
Bernie Wolfe, an army medic, is admitted to Holby, forcing Guy and Ollie to work together to treat her. Serena has to make a big decision over her family secret revelation.
Dominic finds himself in danger when his ex turns up, and there's traumatic consequences. Zosia becomes over-involved with Bernie's army life. Serena gets a surprise.
Dom is cleared by the police following his incident, however he is still under investigation by the hospital. Morven makes a decision about her own health when Austin's liver disease progresses.
Arthur receives life-changing news as he takes compatibility tests to give Austin a new liver. Bernie is back on her feet and works on Darwin for the day, but she ends up breaking the rules.
Ric fights for an old friend's life. Serena is in love with Robbie, and prepares to introduce him to her family. Mo learns she didn't get the consultant position.
Ric throws a tantrum in front of a patient. Morven gets bad news from her father on her birthday, Mo suspects Sir Dennis is a racist. Ric's daughter Jess has blocked his calls, and he is infuriated.
Arthur and Morven's engagement party day and Arthur coughs up blood. Dom quickly takes charge and gets him a scan and a result. Linda is back for a brain scan and it is not good news. Adele decides to go into palliative care.
Jason's care giver has a heart attack and Serena has to make care arrangements until Alan has recovered. Cara starts on Darwin today, and Adele has gone to St. James. Jesse tells Mo that his mother died today.
Jesse's father gets drunk and takes a fall. Mo's mother has heart problems and they all end up in Holby. Sir Dennis misdiagnoses Mo's mum, and her and Jesse operate on her, off duty. Jesse quits, and Sir Dennis is fired.
Mo and Mr. T are fighting over the treatment of a pregnant girl with a disease. Hanssen intervenes. Bernie is shocked to see Alex Dawson on staff, a nurse she had an affair with in the army.
Arthur gets his liver transplant. Zosia get attached to a patient that dies. Arthur's cancer worsens and he won't go home to rest. Tony, a bailiff that serves divorce papers to Bernie, gets bitten by a dog, and she has to treat him.
Fletch is attracted to the new psychiatrist Naomi Palmer. Bernie's husband Marcus is operating on a patient at Holby. She is terrified that someone will gossip about her. She texts Dom, but the text goes to a different staff member.
Arthur's cancer has spread and Sacha tells him he only has a few months left. So he and Morven decide to get married today. Serena's car is stolen with her patient files in it. Hanssen suspends her. Mr. T leaves Holby because Mo rejects him.
Dominic and Zosia both have a difficult day trying to deal with Arthur's cancer. Zosia accuses a patient of leaking a story to the paper about her. Zosia is pushed to the limit and loses her temper. She breaks up with Oliver.
Oliver tries to get back with Zosia, but she catches him kissing Cara. Hanssen shadows Arthur to test his mettle, but Arthur fails in surgery and resigns. Bernie and Serena share the AAU.
Arthur is rushed to Holby with breathing problems. Zosia fights with Jac to give Arthur the new stent she invented. The old man who is supposed to get the stent meets Arthur and decides to let him have it.
Arthur and Morven decide to travel and the staff put on a dance for them. Arthur goes to everyone to say goodbye, and collapses in Hanssen's office. They can't save him this time.
Arthur's funeral and everyone's pager goes off and most of them rush back to Holby. A major train derailment has sent dozens to the hospital. Hanssen is impressed by Bernie's skill, he offers her a job in a new trauma dept.
Jac launches the new "Digby Stent" and the reporters tell her that Berlin launched it a few weeks ago. She now has to find out who is the spy in her team. Dom is shocked that the new registrar is a man he had a date with last night.
Dom is trying to build Arthur's Spanish Galleon model ship. Hanssen sees the ship and finishes it. A psychic patient on the ward tells Dom to "Sail the ship" and he and Hanssen do just that. Dom finally starts to grieve.
Jac got pepper sprayed at a protest outside the hospital, and she can't see what she is operating on. She calls Ollie in to help. He takes a different procedure, and she punches him in the face.
Oliver questions his value at Holby, and thinks about the offer from Elliot to come to Pakistan. Morven is back, and is still grieving for Arthur. Jac is on leave, and Mo takes her place.
Bernie's son Cameron comes in from an RTA. She discovers that her old registrar was a passenger in the car and is pregnant. Cameron says he was driving, but the marks on the woman indicate she was the driver.
Fletch's daughter comes in with a broken neck. His son Mikey confesses to pushing her down the stairs. Zosia treats a patient who says she is her grand mother. Guy does his best to keep them apart.
Jac is back and still holds animosity towards Guy for stealing her stent and selling it to Germany. Hanssen tells her to look after Guy's mother, and she agrees. Fletch's daughter Evie is still in danger.
Dealing with the helicopter crash @casualty, We follow Fletch around for a day in the life of a nurse. The urgent care, the help, and the personal side to nursing.
Mr. T comes back from Sweden with a fiance. Mo can't tell him about the baby. Sacha's birthday and he and Essie decide to break up over the baby issue of their own. Fletch is out of intensive care after being stabbed.
Fletch quickly becomes paralyzed and is having difficulty breathing. Having every test possible, its a race against the clock to diagnose him, until little Mikey tells them about an infection his dad had.
Ric's patient is the woman of his dreams. Isaac's ex comes in for a ruptured spleen, and he isn't quite truthful about their relationship. Jasmine informs Jac that they are half sisters.