Seizing the chance to fix everything wrong with it, Jac Naylor returns to Holby City Hospital as its director of improvement, bringing with her Darwin Clinical Lead Eli Ebrahimi and nurse practitioner Madge Britton. Jac quickly turns heads when she begins stripping down AAU reallocates the funds raised by Jeni for the unit to relocating the neurosurgical unit to Darwin, putting AAU's future in jeopardy, but she quickly becomes overwhelmed by the constant evocation of Kian's memory. Jac quickly concludes that taking the job was a mistake, but Madge assures her that her feelings will pass and urges her to focus on improving the hospital. Jac eventually approaches Chloe about the circumstances surrounding Kian's death and is assured that his overdose was not an act of suicide, and Jac bids farewell to him by visiting the operating theatre he died in. She later overhears Henrik and Jeni planning a coup, and she wishes them luck.
Mohammed Jaziri — a participant in a stent trial Eli is leading — is admitted to Darwin with chest pains and is quickly diagnosed with an aortic dissection. Eli approaches Chloe with the opportunity for her to assist him in the trial, but Mohammed's aorta ruptures during surgery, forcing Eli to pull him out of the project. Jac is furious with Eli's decision, as Mohammed's aortic arch is still intact, making the stent still viable, and warns him about the amount of time needed to find a new trial candidate. However, Eli informs Jac that he will be going ahead with the surgery as per solely Mohammed's wishes and firmly instructs Jac not to interfere with his project.
Madge begins work on AAU and is set on running a tight ship. She falls foul of Ange and Josh when she questions the authenticity of their relationship, not knowing that Ange has just been diagnosed with a case of parvovirus that threatens the safety of her unborn twins, but Madge also shows a softer side when Kylie is groped by a patient.
Dominic has sorted out Carole's assessment plan and booked her in for a menagerie of tests, but Jeong is concerned that Dominic's plan may not be in Carole's best interests. Dominic is still adamant on doing whatever it takes to heal Carole, but the gravity of her situation slowly begins to set in.
- Rosie Marcel as Jac Naylor
- Davood Ghadami as Eli Ebrahimi
- Guy Henry as Henrik Hanssen
- Amy Lennox as Chloe Godard
- Jo Martin as Max McGerry
- Clare Burt as Madge Britton
- Amy Murphy as Kylie Maddon
- Dawn Steele as Ange Godard
- Trieve Blackwood-Cambridge as Josh Hudson
- Debra Stephenson as Jeni Sinclaire
- David Ames as Dominic Copeland
- Chan Woo Lim as Jeong-Soo Han
- Alex Walkinshaw as Adrian Fletcher
- Jaye Jacobs as Donna Jackson
- Julia Deakin as Carole Copeland
- Phoebe French as Evie Fletcher
- Mark Arden as Martin Duffy
- Emma Jay Thomas as obstetrician
- Delroy Atkinson as Delroy Jones
- Ameet Chana as Mohammed Jaziri