In the BBC medical drama’s special festive episode, which aired at the end of 2024, doctor Stevie treated young patient Leah on Christmas Day.

After running some tests, she told Leah’s devastated mum Adele that she suspected her daughter had leukaemia.

Since then, Stevie has had an incredibly difficult time after her assumed pregnancy was actually confirmed to be a cancerous mass on her ovary.

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Her condition rapidly deteriorated and the mass had to be removed in an emergency operation, but the surgeons were forced to perform a hysterectomy to save her life.

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While also struggling with menopausal symptoms, this week, Stevie anxiously prepares for her first chemotherapy session.

She’s reunited with Adele and Leah in hospital, with Lucy-Jo Hudson and Mia Millichamp-Long both reprising their roles for the final episode of current boxset ‘Internal Affairs’.

Leah tells Stevie the good news that she’s received the all-clear, though the girl admits she’s worried about getting ill once again.

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Stevie is frank and honest with Leah, but also gives her some much-needed words of encouragement about the future.

Her run in with a familiar face, as well as one more unexpected gesture, leaves Stevie feeling more hopeful and positive about her own recovery.

Elsewhere in the ED, Rida finds out that Russell has made a counter allegation against her after she bravely came forward about her assault in the operating theatre.

It’s strongly suggested that she signs an NDA, which would involve Russell taking ‘early retirement’ and her leaving Holby for good.

Rida grapples with this life-changing dilemma, though she’s inspired by a patient’s bravery and eventually decides to say her goodbyes.

But the day takes a very scary turn when Indie crashes an ambulance into the ED. Rida and Russell are forced to work together to save someone’s life.

What will this dramatic incident mean for Rida’s future?

Casualty pulls no punches in its emotionally charged and action-packed final episode of the Internal Affairs boxset — an episode that ties together heartbreak, healing, and high-octane drama in a way only Holby ED can deliver.

From tragic personal revelations to one of the most devastating incidents in recent memory, this finale is a masterclass in tension, with characters facing their most defining moments under crushing pressure.

Stevie’s Struggle: From Diagnosis to Determination

Dr. Stevie Nash, whose Christmas Day diagnosis of young patient Leah brought viewers to tears, finds herself on the other side of the stethoscope in this finale — facing her own life-threatening illness with a quiet resilience that is as heart-wrenching as it is inspiring.

After mistaking her symptoms for pregnancy, Stevie was shattered to learn that the mass in her ovary was not new life, but cancer. Her ordeal led to an emergency hysterectomy, an irreversible blow that brought on sudden menopause and left her reeling physically and emotionally.

This week, she returns to Holby ED to begin her first round of chemotherapy — visibly nervous, visibly changed, but still unmistakably Stevie. Her reunion with Adele and Leah, the mother and daughter she once helped through their own crisis, becomes a poignant full-circle moment. Leah, now in remission, offers Stevie a glimmer of the hope she so desperately needs.

Their honest conversation — with Leah fearing a relapse and Stevie admitting to her own fears — is beautifully raw. But the encouragement they offer one another feels real and hard-earned. And when Stevie is met with an unexpected gesture of support from those around her, it sets her on a more hopeful path forward.

Rida’s Final Stand: Truth Over Silence

Meanwhile, Rida finds herself caught in a moral minefield as her complaint against Russell — over his inappropriate behavior in the operating theatre — takes a troubling turn.

In a sickening twist of institutional backlash, Russell files a counter-allegation of misconduct. The hospital’s solution? A cold, clean-slate non-disclosure agreement that would see Russell quietly “retire,” while Rida is paid off and pushed out.

The offer is tempting. A year’s salary. No public scandal. A chance to walk away.

But Rida didn’t become a nurse to be silent.

As she wrestles with the decision, a brave young patient reignites her fire. Rida realizes she cannot make peace with burying the truth — even if it costs her everything.

In a quiet but powerful sequence, she says her goodbyes, walking away from Holby ED not with bitterness, but with dignity. Her courage leaves a lasting impression, especially on those who may be forced to question their own roles in the system.

Disaster Strikes: Indie’s Crash Sends Shockwaves Through the ED

Just when it seems the emotional stakes couldn’t be higher, disaster quite literally crashes through the hospital doors.

Indie, having recently passed her blue lights test, is driving an aged ambulance with Jan as her passenger. But a jammed accelerator turns routine into chaos — and the vehicle slams into the front entrance of the ED in a terrifying sequence that sends debris flying and patients and staff into panic.

The dramatic stunt, teased by Casualty’s official social media channels, is a major turning point in the finale. With glass shattered and the building compromised, a major incident is declared, and everyone — including those in personal turmoil — must spring into action.

Rida and Russell, despite their conflict, are forced to work side-by-side to save a life inside the crash zone. The moment is intense, raw, and symbolic. Whatever their history, in this moment, it’s about the patient — and the oath they both swore.

A Season Ends, But The Stories Live On

This finale doesn’t just conclude a boxset — it encapsulates what makes Casualty a pillar of British drama. Personal pain, systemic injustice, second chances, and the ultimate sacrifice all collide in one unforgettable hour of television.

With Stevie fighting cancer, Rida choosing truth over silence, and Indie facing the fallout of her tragic mistake, it’s clear that the Internal Affairs storyline will have ripple effects for months to come.

Holby ED will carry the scars of this episode. So will the audience.