Film and TV veteran Ed Asner and CBC News chief correspondent Peter Mansbridge are among the famous faces set to pop up in the forthcoming Murdoch Mysteries holiday special.

CBC announced details of A Merry Murdoch Christmas, the first-ever holiday special episode of the popular, early 20th century-set TV mystery series, on Thursday morning.

"The thing that I like the most about having the opportunity to do a Christmas special is that it means Murdoch Mysteries has become one of those shows that is loved and admired by a strong loyal audience," said the weekly drama's executive producer, Peter Mitchell.

The show has seen a host of prominent guest actors join its cast over the years, from this season's earlier episode starring William Shatner as Mark Twain to the July 2011 instalment featuring Prime Minister Stephen Harper as a clueless police officer.

"I am married to an actor with years of experience on stage and in TV and movies – doing news doesn't cut much with that crowd," noted Mansbridge, who anchors CBC's The National, making a reference to his wife, Cynthia Dale.

"I now finally have something to lord over her! I'm thrilled to be involved, even if it's for a very short cameo."

'A real romp'

Brendan Coyle

British actor Brendan Coyle is a stage and TV veteran perhaps best known for playing valet John Bates on Downton Abbey. (Nigel Hunt/CBC)

Actors Brendan Coyle (Downton Abbey) and Kelly Rowan (The O.C.) are also among the guest performers set to join Yannick Bisson, Hélène Joy and the other Murdoch regulars for the two-hour special, currently in production and slated to air Dec. 21.

The Christmas-themed episode revolves around the murder of a local business tycoon and philanthropist during the holiday season and the theft of his gifts for underprivileged children. A further wrinkle turns up when the missing presents are found in the possession of a man (Asner) claiming to be Santa Claus.

"It's a real romp, pretty epic, and I love what I've been asked to do," Coyle revealed to CBC News during a set visit earlier this fall.

The guest stint marks the third Canadian acting gig for the British actor, a stage veteran perhaps best known for playing Lord Grantham's valet John Bates on TV hit Downton Abbey

"It's a very laid-back vibe and this is a well-oiled machine, this show," he said of the Murdoch set.

"I was a little nervous coming in – this is my first day I have a big scene with Yannick, who plays Detective Murdoch – and it was great. It went very smoothly...it's a happy set."

Murdoch Mysteries is based on the popular series of novels by Maureen Jennings. The series, which premiered in 2008, is currently in its ninth season.

A Merry Murdoch Christmas

Murdoch Mysteries actors Yannick Bisson (from right), Hélène Joy and Jonny Harris appear in a scene from the show's forthcoming holiday special, A Merry Murdoch Christmas. (Christos Kalohoridis/CBC)