Back in 2017, the TV legends really got viewers hooked with their Missing Crown Jewels mini-series.
The Missing Crown Jewels followed on from the show's Who Shot Simon Cowell? whodunnit, which saw music mogul Simon murdered at his own party.
The plot involved Ant and Dec being tasked with guarding the Crown Jewels at the Tower of London after receiving their OBEs in the January before.
However, things went wrong when the jewels were stolen and the duo had to uncover who Maskface - the person who stole them - is.
So, who stole the Crown Jewels?
After week's of waiting to see the mystery solved, viewers finally learned who was responsible.
In a British TV first, Ant & Dec's Saturday Night Takeaway was broadcast live from Walt Disney Resort in Florida.
The show saw the final instalment of Who Stole The Missing Crown Jewels as Maskface was unveiled as none other than Ant and Dec's former BFF from SMTV, Cat Deeley.
Cat revealed her plot was to become Queen after feeling overshadowed by Ant and Dec's success following SMTV.
After the revelation, Cat joined Ant and Dec live where they revealed plans to bring back SMTV the following year for its 20th anniversary.
Who starred in The Missing Crown Jewels?
The mini-series included lots of famous faces, from Emilia Fox - who returned to head up the investigation - to Michael Sheen and Alan Shearer.
Other celebrities who made an appearance included Carol Vorderman, Dame Shirley Bassey, Clare Balding, Alan Titchmarsh, Katherine Jenkins, Jessica Ennis-Hill, Gareth Malone and Martin Lewis.
Meanwhile, actress and comedian Joanna Lumley had a very big role in the skit, playing Head of the Honoured - a secret and elite organisation.
She was the person who issued Ant and Dec with the task of protecting the Crown Jewels.
Ant and Dec's Saturday Night Takeaway is on Saturday at 7pm, ITV