Spoilers ahead!
Silent Witness made its hotly anticipated return to our screens on Monday night with its 25th-anniversary series, which saw the return of Amanda Burton's iconic Sam Ryan.
MORE: Silent Witness viewers left worried for beloved character in 25th series return
The opening episode, which is the first part of an instalment titled History, saw Sam join Nikki Alexander (Emilia Fox) in the lab after the murder of health secretary Alice Reynolds.
WATCH: Are you enjoying the new series?
Alice was shot following a press conference held by a company founded by Sam called UNITAS, which led a programme aiming to source organ donors from across the world.
However, the venture meant the company gained a "data goldmine", with access to personal healthcare information that attracted enemies from big tech, who are keen to get their hands on the data.
At the end of the episode, it was revealed that Tom Faulkner's (Matthew Gravelle) fingerprints were found on the murder weapon, suggesting that he may be the killer.
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When his face appeared on Nikki's computer screen, she immediately recognised him, and also had his number saved in her phone contacts. But who is Tom?
Tom becomes a murder suspect at the end of episode one
Tom is ex-military personnel who was born in Cambridge, where the first three seasons of the show were set. He also has connections to Sam and acted as her security detail when she flew out to Stockholm to carry out the post mortem on the murdered politician.
Chatting about Tom's role in the series, producer Nick Lambon teased that viewers are in for a "huge shock" and that the character was a "significant person" in Nikki's past.
He went on to say that moving into episode two, viewers will see Sam question whether Nikki is the one being totally honest.
"Tom and Sam are two people who used to be very close, they used to work together and then they had a falling out." he told Metro.
Is Nikki hiding a secret?
"We made him have a past where he used to work in the army, in Special Ops and private security with Sam, which all makes us believe he can pull the trigger on a gun.
"For Sam, she realises everything is even more complicated than she initially thought because of Tom and Nikki's connection." he added.
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