Casualty on BBC One: Still reeling from Kim's death, the team fight to survive a mystery virus in Lethal Legacy trailer
After the shocking events of last week, this Saturday sees more of Casualty's favourites in danger
Casualty returns to BBC One this Saturday with the episode Lethal Legacy, And, if you’re expecting an easy ride after last week’s utterly harrowing episode, you’d better prepare for the worst.
This week, in Lethal Legacy Part One (episode 1 of 12), the team “fight to survive as a suspected pandemic threatens to overwhelm the ED”. Still reeling from the devastating loss of Kim, it’s more than anyone can bear.
Last week’s episode Learning Curve killed off the series regular, leaving the staff at ED – and viewers at home – in bits. And the upcoming episode promises to be as dramatic.
Here’s a preview of what the BBC have teased about Casualty’s Lethal Legacy so far.
***Warning: spoilers from last week’s episode of Casualty (Learning Curve) ahead***
Preview of Casualty episode Lethal Legacy
After the shocking events of last week, this Saturday (April 26, 2026) sees more of Casualty’s favourites in danger. The new “nail-biting 12-part series of the BAFTA award-winning medical drama” kicks off with the episode Lethal Legacy.
Still reeling from the devastating loss of Kim, the team fight to survive as a suspected pandemic threatens to overwhelm the ED. As the mystery virus sweeps across Holby, the hospital and its residents must face harsh truths as long-buried secrets resurface…
With a surge in patients because of the unexplained virus, the ED buckles under the strain. As a result, the army arrive to keep the peace… However the military presence Flynn to face a past he believed was long behind him. Flynn is confronted with his old CO from the army, the domineering Colonel Jack Bard (played by guest star Mark Womack).
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Colonel Jack Bard’s powerful hold over his subordinates – and his ties to Flynn – threaten to shake the bedrock of the ED when history “begins to repeat itself”.
Meanwhile, Stevie and Matty are still reeling from their recent loss, and turn to an unexpected source of comfort… However, it’s a choice that pushes Dylan away from the son he’s only just begun to know. While Sarah questions Dylan’s commitment to fatherhood in light of the secrets he is keeping.
Elsewhere, Jodie uncovers a disturbing truth buried deep within a local estate, risking everything to expose it… Stevie refuses counselling in the aftermath of her recent loss, and Cam struggles to cope on his return to work.
The trailer for Casualty episode Lethal Legacy can be viewed here.
What happened in Casualty series 40 episode 12 Learning Curve?
Casualty fans were left devastated last Saturday (April 18, 2026) when the BBC One medical drama killed off one of its popular characters. In the episode, entitled Learning Curve, viewers watched with their hearts in their mouths as two characters were in huge danger.
At the start of the episode, a flashforward scene showed the Holby staff gathered in a church to say goodbye to one of their own. But, as Stevie Nash prepared to pay tribute, viewers were left wondering who they were mourning for.
Was the deceased Iain’s pregnant ex-partner Faith? Her waters broke two months early, and she began bleeding heavily and subsequently fell unconscious.
Although Faith’s daughter was born healthy, Faith started bleeding heavily again and collapsed. As she battled for life, Kim lay unconscious at home having succumb to the downfalls of eating disorder.
Both Faith and Kim were in serious conditions, but it was Kim who died from multi-organ failure.
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