At the Hospital de Santa Lia in Lisbon, John Gaskell visits his patient Lana in a private room and reviews the CVs of several members of staff at Holby City Hospital. In Holby, the team watch a video of Laszlo Furz, who claims to have been cured of motor neuron disease by Gaskell using stem cell therapy, praising and thanking the professor for "[giving him] a second life". While Morven expresses her amazement at Gaskell's achievement, Ollie and Raf are sceptical. As Hanssen oversees the relocation of Gaskell's property to the hospital, Jac mocks the hospital's enthusiasm about Gaskell's arrival and asks an optimistic Fletch if he has questioned why Gaskell has chosen to work at the hospital. Fletch hands her a preliminary report to sign, and he informs Jac that Gaskell's team is bringing in a patient named Michael with a spindle cell tumour and want her in theatre with the professor. Jac scolds Fletch for not leading with the information about Gaskell, and, once Fletch leaves, her hands begin to tremble.
On AAU, Essie facetiously suggests that Raf is jealous of Gaskell's appeal after Raf dismisses Laszlo's video as a "propaganda message", and she argues that he should seize the opportunity to "impress an impressive person". On Darwin, Ollie confronts Jac about pushing all of her procedures onto him, but Roxanna and David interrupt and tell Ollie that Gaskell introduced them to each other. Jac learns that there are no theatre rooms available and asks Ollie to page her once Gaskell arrives. Outside the hospital, Sacha, Dominic, Morven, Donna and Lofty wait to greet Gaskell, but they are disappointed when only an ambulance and a wealthy patient arrive.
As Roxanna tells Hanssen that Gaskell is coming to Holby because him and "what [he] fostered", Jac practises her surgical skills on a heart in Gaskell's wet lab. On AAU, a woman named Rosie is rushed in after being dragged out of a frozen lake, and Raf dashes to retrieve the ECMO kit. Donna tells Essie that Rosie needs to pull through as she has cost her a "front-row seat at the meet-and-greet with Professor Marvellous". In the wet lab, Jac quickly packs up the heart as she hears Gaskell approaching, but he appears and tells her that he looks forward to "dancing together". Back on AAU, Raf finishes connecting Rosie to the ECMO circuit, but Essie soon discovers that Rosie is pregnant and warns him of the risks of a major bleed and premature labour. Raf insists that the mother is their top priority, but Donna informs them that Rosie is pregnant with twins.
In theatre, Jac orders Ollie to stand down from the aortic valve replacement he is performing, and he begins to challenge her. Furious, Jac tells him that he has not progressed as expected because he does not have "the mettle, the drive, the ability", and he will never "have even the slightest chance of saving [...] [his] pathetic excuse of a career" if he continues to forget that he works for her. Ollie quietly leaves the room, and Jac continues with the operation. On Keller, Sacha, Dominic and Lofty watch Gaskell, Hanssen, Roxanna and David in the staff room, and Dominic offers to stick a drawing of a woman to Gaskell's door.
In the staff room, Gaskell reunites with his old friends, and they praise him for his achievement in motor neuron reversal. Roxanna asks Gaskell if he can do it again, and he claims that he is "close". However, Dominic interrupts and informs Gaskell that Michael has collapsed en route to the hospital. At the entrance, Ollie introduces himself to Gaskell, and Gaskell explains that Michael's autonomic system has shut down due to compression of the spinal cord. In the lift, Ollie asks Gaskell how he managed to get approval to use a tissue scaffold laced with progenitor cells on a patient and attempts to inquire further, but Gaskell proposes that they speak some other time. Ollie is surprised to find David on Darwin and asks if he is there for Roxanna's virtual reality simulator, but David claims that she scrapped the project after concluding that he was not a viable candidate, and she needs to focus on supporting Gaskell.
On AAU, Raf asks Essie to run an EEG on Rosie to assess her brain activity, but Essie highlights coincidences, such as her recommending Raf to impress Gaskell and Raf being forced to use a technique he introduced to the hospital, and both Rosie and Kim having twins; Raf urges her to trust the science, not superstition. Donna interjects and tells them that there is "something [they] should come and see". On Keller, Ollie confronts Roxanna about her abandoning the VR project and demands the "tiniest sliver of respect" for him and his career. Lofty approaches Ollie and tells him that David stumbled when he tried to ask him for some notes, and one of the other nurses described him as becoming more aggressive, but Ollie insists that David is more lucid than Roxanna has led him to believe and orders Lofty to get on with his job. Back on AAU, the team review Rosie's ultrasound and find a third foetus, and Raf suggests that it is showing superfoetation.
On Keller, Fletch asks Sacha of Jac's whereabouts, but Dominic presents them with Gaskell's drawing which he has framed; Sacha assures him that Gaskell will appreciate it. On Darwin, Ollie informs Jac that he feels "empty" on the ward and demands her to acknowledge his resignation. Jac hands him a patient's case notes and asks him which artery comes off the aorta to supply the spinal cord with blood, but he is insisted on leaving at the end of the day. Jac loudly orders him to sit down, and Ollie asserts that he would want more reassurances about Michael's clinical trial than just Gaskell's. Ollie claims that Jac owes him an apology and suggests that she is "terrified", but she claims that she is astounded by his "arrogance", and his "stupidity is breathtaking".
Back on Keller, Gaskell explains to the team that he will 3D-print the scaffold and insert it into Michael's spinal canal, but Jac insists on being fully informed about Michael's condition and having the procedure performed on Darwin. Sacha apologises to Gaskell for Jac's attitude, but Gaskell sympathises with her, citing Jasmine's recent death. On AAU, Raf assures Essie that Rosie's condition is improving, but Essie claims to have lost her wedding ring and avers that her discontent is not based in superstition. Raf asserts that he trusts ECMO as he gives him control and allows him to operate "outside of the margins". Donna pulls Essie away for a meeting with Gaskell, and Raf urges Essie to stop thinking the loss of her wedding ring "symbolises Armageddon".
Meanwhile, Jac struggles to keep her composure on Darwin while Sacha expresses his concerns about Gaskell's reluctance to have Laszlo's condition reviewed by other medical professionals. Realising that Jac is showing signs of anxiety, Sacha tells her that he practises his bloods triads in his head when he is apprehensive about an operation, but Jac indicates that she wants him to stop and sits in despair; Fletch goes to comfort her. In the wet lab, as Gaskell prints out the tissue scaffold, he tells the nursing staff that he is only interested in the end goal and needs them to continue providing "the environment that [they] do so immaculately". Donna points out that the hospital is "falling apart at the seams", but Gaskell clarifies that he is talking about their passion and desire to enjoy their work. Elsewhere, Sacha calls Hanssen to express his concerns about Jac and his guilt over not realising that she also needed support when she supported him in his depression. On their way out of the wet lab, Gaskell finds his drawing "caged up" in the frame and suggests to Essie and Donna that the frame shattering could be seen as a "catharsis" or "a chaos". Gaskell hands the frame to Essie who promptly drops it.
In the Darwin theatre scrub room, Jac insists to Gaskell that she is "never nervous", but Gaskell acknowledges that his predecessor Guy Self performed a similar procedure and claims that he is here to replace anyone. On AAU, Donna shows Raf the threats Jeremy has been directing towards the hospital and Jac specifically, but Rosie begins groaning in pain, suggesting that the shock of the hypothermia may have triggered labour; Essie decides to look after Rosie's son Ezra as the medics treat his mother. In theatre, Roxanna talks Jac and Gaskell through the vascular isolation and tumour resection procedures, and Jac reluctantly proceeds. On AAU, Essie disagrees with Raf's decision to perform an emergency caesarean on Rosie and warns him of the chances of a major bleed and a potential hysterectomy; Raf questions Essie's trust in him. Donna informs Raf of a bleed between Rosie's uterus and placenta, and she asks if she needs to scrub in, but Raf assures her that he will be fine.
David, Ollie and Lofty observe Michael's operation, and Ollie remarks to David about the surrealness of watching his old classmates performing surgery together. However, David does not recognise Ollie and quickly forgets what he is watching. Ollie informs Roxanna about David's deteriorating condition, and Gaskell urges her to go as Michael begins to suffer a major bleed. On the ward, Ollie apologises to Roxanna for dismissing Lofty's concerns about David's health and jumping to a false conclusion based on "[his] own dented ego", but Roxanna admits that she abandoned the project "for false hope" as she noticed that David showed a greater level of memory retention in a clinical setting. However, Lofty interrupts and informs them that David is slurring his speech and showing symptoms of a stroke.
In theatre, Jac prepares to stitch the aortic graft, but, as Sacha and Hanssen arrive to observe her, she contends that she cannot complete the procedure and bursts out of the room. Outside, Jac accuses Gaskell of being unethical and feeding off of the other staff's uncertainty, and he insists that, like him, she needs disorder to "see coherence", and he needs Hanssen and the others to witness what his treatment can do. Jac asserts that Gaskell has everything to lose, but Gaskell claims that he has been to the same "place" as her and urges her to help him. In the operating theatre, Sacha is saddened when Gaskell returns with an emotionally drained Jac. On AAU, as Raf struggles to stabilise Rosie, Donna tells Essie that she cannot attach meaning to the situation.
On Darwin, Gaskell attempts to insert the tissue scaffold, but Michael has an immune response to the growth medium. After the clip detaches from the artery of Adamkiewicz, Gaskell instructs Jac to stitch it. However, she begins to struggle and is forced to use a pledget to plug the vessel. Distressed, she recites her triad of bleeding. On AAU, Essie watches in trepidation as Rosie's newborns are individually wheeled out of the operating theatre, but she is soon delighted to learn from Raf that he managed to stop the bleed. In the theatre on Darwin, despite successfully stopping the bleed, Jac breaks down and runs out. Fletch finds Jac in her office and tries to calm her down, but she becomes hysterical and insists that she is nothing without surgery. Fletch asserts that she needs to acknowledge what happened to Jasmine, Fran, Guy and Zosia, and he comforts her as she sobs in his arms.
On Keller, Gaskell and Ollie inform Roxanna that David has a patent foramen ovale which has exacerbated his dementia, and they praise Lofty for his observations. On AAU, Raf entertains Ezra with an impression of Wolverine, and an excited Donna informs Raf and Essie that the spinal implantation was successful. On ITU, the medics express their amazement as they watch a previously paralyzed Michael move his toes, and Gaskell decides to show them one more thing. In Jac's office, Fletch posits that she was scared of letting in her grief in case there was no end. Jac admits that she lost control and was surprised to see a better version of herself in Gaskell; she asserts that she now has clarity, but she disagrees with Gaskell that it "means the end". Morven interrupts and informs the two that David has a PFO and requires the Darwin theatre; Jac tells her that Ollie can carry out the procedure, and she can observe for her CT training. Once Fletch leaves, Jac returns to her desk and smiles when she finds one of Emma's drawings.
In the wet lab, Gaskell tells Hanssen and Sacha that, when he found Laszlo, he only had weeks to live; by the following year, he had fully recovered from motor neuron disease. To Hanssen and Sacha's surprise, Laszlo emerges from a neighbouring room and introduces himself. On Darwin, Jac packs her bag and leaves her office. She apologises to Ollie and admits that she was afraid; she claims that, despite all of the cuts and managerial chaos, he remains "constant", and she urges him to stay and become the consultant he "should be". He thanks her, and he tells Morven that Jac is leaving. Meanwhile, Laszlo encourages Hanssen and Sacha to use him as their case study, and Essie is awestruck to discover that the story about him was true.
On the staircase, Jac bumps into Raf; she tells him that she is leaving Holby for good and asks him to hand her letter of resignation to Hanssen. Raf suggests that she is acting purely out of self-interest, but she asserts that she is a mother, and "that's all there is". As Jac leaves, she sends Fletch a message asking for a word. However, she encounters a person in the basement and looks at them in horror. In the wet lab, Hanssen, Sacha, Gaskell and Essie hear a loud explosion. Nearby, Jac, who has been shot, groans in agony and collapses.
- Rosie Marcel as Jac Naylor
- Joe McFadden as Raffaello Di Lucca
- Paul McGann as John Gaskell
- David Ames as Dominic Copeland
- Bob Barrett as Sacha Levy
- Jaye Jacobs as Donna Jackson
- Eleanor Fanyinka as Morven Digby
- Lee Mead as Ben "Lofty" Chiltern
- Hermione Gulliford as Roxanna MacMillan
- James Anderson as Oliver Valentine
- Guy Henry as Henrik Hanssen
- Alex Walkinshaw as Adrian "Fletch" Fletcher
- Kaye Wragg as Essie Harrison
- Daniel Vivian as Laszlo Furz
- Fraser James as David Hopkins
- Joe Citro as Ezra Cranham