Jac, Ric and Sacha face off against old rivals while pitching for a million-pound prize fund. But as the competition threatens to divide the group, should they be more worried about their friends than their enemies? Serena's new year is once again marked by tragedy when a loved one is brought in for emergency surgery. Dare Serena put her personal feelings aside and perform the operation to prevent history repeating itself?

A surprise blast from the distant past returns to run a Young Adult Unit alongside top consultant Ange Godard. He successfully puts everyone on tenterhooks with his notorious barbs and quips, until things take a surprising turn, much to everyone's surprise. Nicky competes with Cameron for the junior doctor lead position only to realise that high accolades aren't everything when it to come to surgery. Serena steps in to protect her ward when an old face from the past turns up and offends them. Serena fails to see the funny side and takes control.

Ange finally allows Dominic the chance to work on her new unit, after much persistence, but she isn't sure whether he has the chops to be a great doctor. When Dominic is economical with the truth, Ange has to confront him and then feels that he's not trustworthy. Nicky and Cameron find common ground when they have to work alongside an unforgiving Jac. Struggling to prove that he's worthy, Cameron goes all out to impress her. When things go wrong, will Cameron be forced to confront his own mistakes? Ric's former wife Lola returns to Holby to work alongside her former flame on AAU. Serena and Zav are highly amused by the tension between them, but Ric soon realises that he actually has residual feelings for his ex. But are they reciprocated?

Frieda is happy her life is on an even keel, but her contentment is shattered when her ex-boyfriend Roman unexpectedly reappears. Can a wary Frieda open her heart and dare to imagine a future she had thought was gone for good? With their relationship going well, Xavier is keen to step up and ease the burdens weighing on a stressed Donna. But all does not entirely go to plan when Zav embarks on some impromptu parenting of Mia. Ange feels the pressure as she works to sell her vision for her Young Adult Unit while treating a difficult and vulnerable patient. But striving to be all things to all people, Ange fails to get to grips with the behaviour of a returning colleague who might really need help.

When Holby is overwhelmed by a winter crisis, Ric goes above and beyond to treat his patients. But as the pressure reaches fever pitch, can he continue to accept Holby surviving on nothing more than good will and the occasional miracle? To Jac and Fletch's concern, a grief-stricken Frieda immerses herself completely in work, but when she's challenged by a patient's confrontational father, and with her emotions running high, Frieda embarks on a fight she has to win. When Ange has her work cut out on YAU thanks to an obstinate teenager, it's down to Essie to persuade an unwilling Ange to enlist help from a source who's a bit too close to home.

When a family secret is exposed, the dispute causes a young patient to delay vital surgery, but fearing the consequences of such a decision, a concerned Ange must find a way to make her reconsider. Keen to highlight the constant pressures Holby faces on a daily basis, Ric enlists the help of an influential acquaintance. But when an innocent patient is caught up in his personal crusade will Ric do the right thing? When the opportunity to attend an overseas conference arises, Nicky and Cameron must battle it out, but with Nicky running on empty does she have the strength to come out on top?

While Holly's condition weighs heavily on an emotionally invested Ange, Holly's distraught parents must put their differences aside to make a heartbreaking decision, but are they prepared for what lies ahead? When new locum Chloe covers on Darwin, a smitten Cameron sets out to impress, but with a tricky patient keeping him on his toes will Cameron step up to the plate? There's no love lost between Xavier and Carole, so when a disgruntled Xavier is tasked with treating spiritual Carole, it's clear she's not the only one in pain.

Zosia arrives at Holby keen to get back working on Darwin. With her knack for irritating Jac in full swing, will Jac be able to track down Frieda before Zosia gets too comfortable? Ange struggles with Holly's parents who are intent on fighting for their daughter. When an offer of hope for radical treatment comes from America, Ange does her best to make them see what is really best for their daughter. Donna and Xavier struggle to keep their domestic arguments at home - will being forced to work closely together for the day sort out their differences or drive them further apart?

Zosia's big news gets a mixed response, and Jac remains suspicious about her real reasons for returning to Holby. Zosia's situation is further complicated when a handsome American turns up wanting to tempt her back across the Atlantic. Sasha is rattled and embarrassed when an old flame appears on the ward with their ill partner. Following diagnosis, Sasha gets to try out his new transplant procedure and by the end of the day has two reasons to celebrate. Following an incident with protestors, Jason refuses to leave Hanssen's office until his demands are met. Despite Serena’s pleading, he stands firm and eventually a difficult decision is made about a long-term patient, much to Ange’s annoyance.

A computer virus shuts down Holby’s power, putting Jac and Connie at loggerheads as they fight against all odds and in makeshift conditions to save the lives of close friends and colleagues. During a hospital-wide evacuation, Ric mounts a daring rescue for a trapped and weakening Essie – even as he struggles with a shocking revelation about Darla. In the midst of chaos, can Ange and Serena agree on how best to care for Holly, who continues on life-support?

A desperate Ange pleads with Holly’s family to see reason, but when the ruling comes back, the anger finally boils over with devastating consequences for Fletch. Ric's son Kofi arrives at Holby wanting to find out what’s going on with Darla. Struggling to keep his granddaughter's pregnancy a secret, Ric battles to keep his family together and do what’s right for everyone. An excited Zosia looks forward to working with Frieda, only she doesn’t get the reception she was expecting. As the pair team up to tackle a case, Zosia does her best to win over Frieda, with hilarious results.

As the protesters grow angrier Holby tightens security, Fletch realises there may be darker forces at play with Theo’s disappearance. Chloe struggles to decide if staying at Holby is the right thing to do. Dom tries to persuade her, but is thrown off by a surprise visitor. A romantic evening doesn’t go as planned for Xavier and Donna when his mother arrives, putting Donna in a difficult position.

Ange follows a hunch and ends up uncovering a shocking and long buried secret – one with the potential to tear her life completely apart. A downbeat Frieda faces tough choices when an old friend of Roman’s appears in Holby in desperate need of help. Can she manage to work within the system and play by the rules? Cameron and Xavier are forced together on Darwin, where Xavier appears to take delight in Cameron’s dating woes.

Chloe is surprised and immediately wrongfooted when ex-boyfriend Evan unexpectedly turns up on Darwin Ward. Is it possible he’s simply there to care for his sister Phoebe? As Ange reels from her recent earth-shattering discovery and tries to plan her next move, Carole unexpectedly confronts Dominic with painful and long-buried secrets from his past. In the midst of a chaotic shift, Donna is surprised by Mia’s unexpected appearance – forcing Donna to navigate some sensitive parenting territory.

A bewildered Dom struggles to come to terms with a shocking family secret and he immerses himself in work. However being around Ange proves difficult, causing Dom to make a drastic decision about his career. Will Ange convince Dom to change his mind? Donna will do anything to protect her daughter, but when she oversteps the line in a well-meaning attempt to shield Mia, Donna’s parenting is called into question. Though Serena offers some sound advice, can Donna accept Mia is growing up? An enthusiastic Zosia is keen to take on more challenging cases but Jac, still privately resentful towards Zosia, sidelines her. Feeling disgruntled, Zosia undermines Jac’s authority, but it only adds strain to their already fraught relationship.

A startling incident forces Zosia to reconsider her future at Holby, Cameron has to treat a close relative of Xavier's, and Dom tries to keep Carole at arm's length.

Jac’s top-dog status is challenged when a talented new surgeon starts at Holby and instantly causes a stir. Dom is irritated when Carole starts work on reception, and Ange tries to limit family fallout. Donna is flattered to be offered a new career opportunity, but does she really want the extra responsibility?

Kian’s big personality and alternative methods are beginning to grate on Jac, but is it just a case of professional jealousy? Fletch reminds her that she’s only as good as her team and should allow him to thrive. Dom tells Ange he wants to be a proper part of her and Chloe’s lives. In response Ange finally opens up to Dom, revealing a big family secret. When Sue makes a big mistake on her first day at the new job, Donna covers it up. However being the favourite of the new boss poses new challenges.

Ange plans to tell Chloe her biggest secret, but a surprise locum throws her day into disarray. Ric’s granddaughter, Darla, arrives at Holby, forcing Ric to deal with her pregnancy head on. Kian rallies Nicky and Cameron to help him find out who Jac’s mystery patient is.

As Chloe tries to come to terms with the news that Dominic is her half-brother, she’s forced to operate with him and Ange. But as tension boils over and Evan helps her uncover a home truth, will Chloe be able to cope? Lofty returns to Holby after the holiday of a lifetime. With something clearly on his mind, he wants to speak to Dominic but misses his moment when he learns that Ange is Dominic’s birth mother. But what is Lofty hiding, and who is just around the corner? When an infestation of rodents takes refuge at Sacha’s home, he decides it’s time to move out of Jac’s house and leave her in peace. Jac worries whether he’s really ready, but what will Sacha do to convince her?

Dominic faces his difficult past when he goes head to head with his abusive ex, Isaac. Ange and Carole band together in order to cope with the fact that Isaac has returned, affecting Dominic’s life. Jac’s conscience is thrown into conflict when she meets a previous patient who has something she wants. How far will she go for personal gain?

Will Lofty and Dom’s marriage survive under the pressure of Isaac’s presence at Holby, and is Sacha’s relationship with Patricia over before it’s even begun?

As Dom and Isaac grow closer, is Dom at risk of falling under his spell? Hanssen finds himself in unfamiliar territory when an estranged relative arrives at Holby, and Chloe gets an unpleasant surprise when she returns to work.

The manipulative Isaac continues to drive a wedge between Dom and Lofty, but when Isaac puts Lofty in harm’s way and the net is closing in, is Isaac’s fate sealed? Good intentions backfire for Cameron when an intervention doesn’t go his way, but when faced with an opportunity to protect Chloe, Cameron makes a selfless gesture. Hanssen must navigate the world of parenting to figure out what’s troubling his unusually quiet grandson Oskar.

When Xavier’s mum arrives on AAU talking in riddles, Donna does her best to shelter him from her behaviour - but will he appreciate the intervention? Sacha makes a romantic gesture but finds something unexpected in Patricia’s cleaning cupboard. Nicky turns her nose up at working with Jac, who ensures she’ll live to regret it.