Chrissie visits Owen after taking a pregnancy test, fearing she may never be able to have children. Dean learns a lesson whilst shadowing Diane.

Parts three and four of a two-hour "Casualty@Holby City" special aired in four parts over consecutive weeknights. For parts one and two, see Casualty S20E09.

Lola discovers there is nothing wrong with asking for help. Mickie battles against rules and regulations only to find out that they are put there for a reason. Dean relises he can't put his personal pride before a patient.

Mark is forced to leave the comfort of Darwin for the chaos of AAU. Elliot crosses Connie again and Donna oversteps the mark with disastrous results.

Ric performs extreme surgery on one of his patients, with disastrous consequences. Owen finally decides between Chrissie and Diane, and Matt bumps into a face from the past.

Diane passes her consultant's exam, but is she ready for promotion? Connie learns that Elliot can be a pillar of support. Meanwhile, Dean's future hangs in the balance.

Lola finds Amy drinking heavily in an attempt to cause a miscarriage. Donna decides to contact social services, but the troubled teenager's stepfather has other ideas and secretly arranges for her to go to another hospital. Chrissie tells Owen she is leaving Holby, forcing him to finally make a choice between her and Diane.

Abra returns to Holby with his nephew, who needs an urgent transplant. Ric is unable to operate because of the injury to his hand - but he relents when the patient's mother reveals a secret. Owen fears that he might get sacked for hitting Amy's stepfather, and that this could jeopardise his access to Katie. Diane tries to keep Laura from turning on her ex, but when she learns about his clandestine relationship with Chrissie, tragedy strikes.

Owen brings Katie to work to see the counsellor, as he is worried she is becoming too withdrawn. He also makes plans to spend Christmas with Chrissie, but when he overhears his daughter talking to Diane, he realises he must be clear about where his priorities lie.

Amy is brought in for treatment following her miscarriage, and Nigel announces his intention to take legal action. However, Roz is beginning to suspect the truth about her husband.

Part two of a Casualty@Holby City crossover. For part one, see Casualty S20E17.

Two medics apply for the registrar's position, and Connie sees an opportunity to advance her own career when she learns one of the candidates has a very influential father (guest star Ronald Pickup).

Mickie is offered a job as a nurse, but her mother urges her not to take it. Mark and Tricia reminisce about old times while treating a patient - but when it emerges that the woman was raped, bad memories come flooding back.

Ric has plenty of problems on his hands as the new ward opens - the thermostat breaks down and he is forced to take charge of an operation personally. Diane and Chrissie get into a heated argument over Owen in front of a patient, while Donna applies for a new job. However, she is surprised to learn Mickie has already been appointed, and wonders why she didn't say anything.

Frank's life insurance company asks for his medical records, and Tricia is afraid Mark will find out her secret. Despite her best efforts to cover things up, she is ultimately forced to confess that Chrissie is not his daughter. Jac returns to the hospital and Ric advises Diane that she should take some time off to deal with her personal problems - though she's adamant that it isn't necessary.

Jess returns to work after the death of her son but finds her newfound determination put to the test when young patient Archie presents with a lacerated spleen and she suspects possible child abuse. Meanwhile, Mark tries to deal with the news that Chrissie is not his daughter.

Connie's old school boyfriend Peter Holland arrives in the emergency department with a case of rheumatic fever and reveals childhood secrets about Connie. Mark and Lola become very involved in the treatment of two young brothers who have been beaten up. Elsewhere, Mickie loses her drunk patient Liz.

New nurse Kyla abandons a patient during a critical period and the rest of the team want answers. Meanwhile, in a bid to get Ric's support Jac and Diane go head to head in their procedures.

Sam performs a risky operation that he has never done before - to Connie's outrage. Elliot gets a new PA, but finds she cramps his style, while Chrissie receives a variety of Valentine's gifts from a secret admirer. Paul Nicholas guest stars as a patient whose vasectomy reversal goes horribly wrong.

Jac's determination to have Ric choose her as the new consultant has tragic consequences. Sam bends the rules again and is brought down to earth with a bump. A determined Lola fights to keep Princess at home.

A woman comes in for a heart transplant, and Connie persuades her to accept an experimental procedure that has never been tried before. Ric leaves Nick in charge while he is at the university, but Jac does not approve of his handling of a cancer patient's treatment and a past conflict between them resurfaces.

Mark gets over involved in a case which causes disastrous consequences. Meanwhile, Nick Jordan rocks Diane's world which may affect her relationship with Ric.

When Nick learns that Ric is away from Holby for the day he is determined to get one over on him. Meanwhile, Kyla learns that the best way to be a leader is to be herself.

Matt's parents want him discharged from hospital to be treated at home, while Mark blames himself for the stabbing. Donna flirts with a handsome physiotherapist, though Kyla warns her to stay away from him. The treatment of a heart patient causes conflict, as Connie wants to try the manufactured pump she helped develop, but Elliot is adamant a transplant is required.

Nick performs an unnecessary operation in his campaign for a transfer. However, when the patient's condition worsens, Jac is forced to take matters into her own hands. Matt and Dean undergo a student assessment with Lord Byrne, but may not be up to the challenge. Mark is plagued by his secrets as he treats a woman with problems similar to his own.

Connie is devastated when her patient collapses and there's not enough time to arrange a heart transplant. Nick tries to get Diane on his side by letting her perform a difficult procedure for the first time, while Ric talks her into taking the research position full time. Kyla brings Max to work as he is a diabetic and she is worried about his blood sugar levels.

Elliot fears for his wife, who has motor neurone disease and whose health appears to be getting worse. He also regrets their decision to keep her condition a secret from Martha - not realising she knows something is up and has persuaded Joseph to help her learn the truth. Sam uncovers a family secret when he treats a boy with two mothers who is undergoing a heart transplant.

Ric risks his friendship with Diane in an attempt to save her from Nick Jordan's clutches. Meanwhile, Joseph finds himself in trouble at work and Matt makes a career changing decision.

Diane is determined to prove Ric wrong about Nick Jordan and a desperate Tricia tries to keep the truth from a suspicious Chrissie.

Joseph struggles to stay in control as tension builds between Nick and Ric. Donna is thrilled to have a new man in her life but can Justin really give her what she truly needs?

Helena develops complications following Nick's rushed surgery, putting Diane in a difficult position when she realises the problem should have been noticed during the first operation. Sam breaks the rules to help a recovering alcoholic who needs a heart transplant after learning the patient has a young son, and Justin tries to flirt with Kyla again.

An inquest into the death of Helena Bosman throws the spotlight on Nick and Diane. Meanwhile, Sam plays a practical joke on Joseph.

Diane is told to work under Ric's supervision when she is blamed for Helen's death, but she is determined to clear her name and attempts to secretly record Nick confessing to his error. A new assistant general manager starts work at the hospital, and soon invites Donna to the May ball, while Matt gets a second job in the admin department to pay off his debts.

Abra supervises Diane as he covers for Ric for a fortnight, and reveals he would be keen to work at the hospital permanently - but his determination to perform an operation tempts him to bend the rules, and ruins his chances. Tricia tells Chrissie about her relationship with Mark, and decides to have her surgery moved forward.

Chrissie panics when Don Bosman returns to the hospital to get Helena's body and finds out her heart was donated without his consent. Dillon's condition worsens after being readmitted, leading Sam to discover he has failed to conquer his drinking habit. Meanwhile, jealousy gets the better of Kyla, who berates Justin for behaving unprofessionally after catching him flirting with Donna.

Elliot lets his personal feelings get the better of him when Gina is re-admitted. Sam is put on report but continues to do things on his own terms - will he learn his lesson?

Nic Jordan steps up his campaign to get back into CT. Mark tries to save Chrissie from a painful truth, but unearths shocking news about Tricia.

Jordan helps Connie save the day when a black tie charity dinner turns into a disaster zone. In an attempt to ingratiate himself with Kyla, Justin offers to look after Max.

Matt tries to raise some money by signing up for clinical trials, after his landlord evicts him over unpaid rent , and Lola is angry when she receives a postcard from her globe-trotting daughter. Donna helps with a drugs audit, but ends up flirting with Bradley.

Bradley outlines his cost-cutting plans for the hospital, dividing opinions among the staff, especially when he suggests they could perform more operations to earn a £3million bonus. Joseph returns to the wards, but it is clear his OCD is not under control when he insists on scrubbing his hands repeatedly and fumbles a simple procedure.

Lola makes a drastic decision regarding baby Leeanne's care. Reg wonders if Bradley's intentions towards Donna are honourable. Jac works closely with Joseph.

Michael faces his appeal hearing, and uses the opportunity to try to patch things up with Connie, while Sam shares a secret with Chrissie. Lola discovers Leanne's father Steve has been admitted, and becomes convinced he is a drug user.

Connie's heart battles her mind as she wonders if she should stay at Holby. Mark learns to respect the way Tricia wants to handle her cancer.

Matt arrives for his first day in the hospital as a doctor, but soon realises how hard the role will be when he begins to suspect an elderly woman is being bullied by a foster child, while Elliot meets Gina when she arrives for an appointment. Reg becomes flustered when he sees Donna walking out of the staff shower, and grows increasingly jealous of her relationship with Bradley.

Matt and Donna row over Bridie's death, with both keen to blame the other, but the arrival of the nurse's grandmother visiting her boyfriend in the hospital gives the doctor a chance to offer an olive branch. Connie offers Sam a position as trainee rep as the pair grow closer, much to Chrissie's annoyance, and a patient's dad asks Lola out on a date.

The hospital staff have their work cut out after a car pile-up, giving Kyla the chance to earn some extra money to put toward her legal fight to keep Max. After their night of passion, Connie and Sam flirt with each other despite professional disagreements as they treat an injured couple, and Mark prepares to pop the question to Tricia.

Abra returns to the hospital, but Ric is not happy to be working with him - especially when he learns the surgeon has been making promises to patients that he will struggle to keep. Meanwhile, Mickie develops a crush on a patient, but is worried asking her out may harm her chances of getting into medical school.

Abra tries to help a patient waiting for a transplant by offering to operate with an animal organ, despite the procedure being illegal, and asks Mickie to help him in theatre. Elliot monitors Margaret's condition as she returns from her stem cell treatment in Singapore, believing her case mirrors that of his wife, Gina.

Lola must persuade a reluctant Ric to help her to gain custody of Leanne.

Tricia becomes emotional when her attempts to reunite a dying man with his drug-abusing son are too close to home, and Mark organises a rushed wedding with the ailing nurse. Matt struggles to understand why his patient won't respond to medication, questioning whether Donna administered it correctly, while Chrissie and Kyla argue over the running of the ward.

Gina puts Connie in a difficult position when she asks her for help behind Elliot's back. Connie must then decide where her loyalties lie. Ric's skills are tested when he has to operate on an obese woman. Matt and Reg find more evidence of drug tampering.

Gina again asks Connie for advice. Connie feels stuck between her friendship with Elliot and her proffesional duties. After discovering some of Bradley's actions, Ric is determined to get to the bottom of the drug tampering case. Bradley decided to help out Ric.

Connie accompanies Gina to Switzerland for her assisted suicide, but cannot bear the thought of Elliot not being there and calls the doctor, who immediately flies over. Bradley finalises his move to St Luke's, but angers Donna by referring to her as an 'ally', and a drug-abusing patient reminds Joseph of his own problems.