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Silent Witness season 25 ending explained: One final twist

The anniversary series delivered a dramatic conclusion. ***MAJOR SPOILERS AHEAD***

Nikki Alexander in Silent Witness wearing a forensic suit and looking concerned while at work
Published: Wednesday, 8th June 2022 at 9:20 am
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Last night, there was another significant development in the penultimate episode of Silent Witness season 25.


Jomo Mashaba's son David and his wife Fiona pledged to reveal the identity of the Big Bad in exchange for protection. Their request was granted and the couple were whisked off to a safe location, accompanied by DS Martine Chalal.

But they didn't make it to their final destination.


Silent Witness season 25 ending explained

The trio were involved in a serious collision, in which the detective lost her life. Fiona was also left in a critical condition. David, however, was able to limp away from the wreckage.

It later emerged that the crash had been planned to ensure that David and Fiona kept their mouths shut about the identity of the puppet master or masters. Initial evidence indicated that the lorry driver had gone into anaphylactic shock while behind the wheel, but further examination revealed that he was a hit-man who had purposefully eaten fish containing a toxin which mimicked a severe allergic reaction, rather than causing one.

Before David fled the scene, he stole Chalal's phone, which he later used to make a call.

"He will speak to me because if he doesn't, I'll talk," he said.

A short time later, David was killed.

When Detective Superintendent Ronnie Boyle tracked him down, he found David with a bullet wound to the head. The assassin, who had remained at the scene, then attempted to kill him. But just in the nick of time, Jack Hodgson swooped in and prevented Boyle from meeting a grisly end.

Despite Jack's best efforts, the gun-for-hire managed to escape, with the authorities still in the dark about who was responsible for the murders – that is until they uncovered one particular call made by David before his death.

Simone, Jack and Nikki wearing forensic suits and standing next to an ambulance
Dr Simone Tyler (GENESIS LYNEA), Jack Hodges (DAVID CAVES) and Dr Nikki Alexander (EMILIA FOX). BBC/David Emery

He had reached out to Ethan Daley, the brain behind surveillance and monitoring network Vigil. The government had invested millions of pounds in the technology, with police forces up and down the country utilising it in their investigations.

In response to that development, Nikki Alexander examined Lewis Daley's medical records – Ethan's son had been arrested on suspicion of killing his wife – to see if there was anything they could run their samples against – and there was a big discrepancy: Lewis had Hepatitis C, but there was no evidence of that in the blood found under his step-mother's fingernails.

The evidence against Lewis had been fabricated by Fiona, just as Tom Faulkner's DNA had been manipulated to frame him for murders he hadn't carried out.

Through David, Ethan was hoping to gain access to Unitas Health's intelligence to bolster his data domination. Health secretary Alice Reynolds wanted to block that contract, which resulted in her death, and anyone else who tried to obstruct his route to the top was also snuffed out.

But Ethan wasn't working alone. Oscar Harris, a government special adviser, was also involved in the scheme.

oscar Harris Silent Witness standing in the forensic lab
Oscar Harris (DAVID LEON). BBC/David Emery

Ethan needed someone in government to lobby for Vigil and Oscar was more than happy to oblige, for the right price. Oscar would ensure that the necessary palms were greased, with Vigil's critics, such as Alice and journalists Dan Clemence and Oliver Meehan, silenced.

Before long, Vigil's power was unmatched and Oscar's pockets fattened significantly.

But there was still one piece of the puzzle left to solve: what had happened to Sam Ryan?

Oscar managed to locate her thanks to Simone Tyler's research. She was holed up in an abandoned building, very much alive, with a makeshift laboratory. Having twigged that Oscar was corrupt, she decided to fabricate his DNA using Fiona's research as guidance, and she was successful.

Oscar planned to have Sam killed, but his fabricated DNA was her insurance policy. If she was killed, his samples would be released and ultimately implicate him.

He demanded that she recall the samples, but Sam refused and his henchman moved in for the kill.

Fortunately, Tom rushed in and shot the assassin, before turning the weapon on Oscar. But before he pulled the trigger, Nikki appeared and convinced him not to act – and initially, he listened to her advice.

Amanda Burton as Sam Ryan in Silent Witness wearing a white forensic suit
Professor Sam Ryan (AMANDA BURTON). BBC/David Emery

Ethan was arrested while trying to leave the country, as was Oscar. But there was one final twist.

Nikki received a text from Tom which read: 'I can't let it go. I'm sorry.'

He posed as Oscar's lawyer to gain entry to the cell he was being held in.


"It's all over now," he said, before taking a step towards him. We weren't privy to what happened next, but we assume it didn't end well for Oscar.

Silent Witness season 25 finale airs on Tuesday 7th June at 9pm on BBC One. Check out what else is on with our TV Guide, or visit our Drama hub for all the latest news and features.

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