David Duchovny and Gillian Anderson - aka FBI Special Agents Fox Mulder and Dana Scully - are back together once again.

Gillian Anderson and David Duchovny starred as Dana Scully and Fox Mulder in The X-Files in the 1990s.

In a new case for Mulder and Scully, the cast of The X-Files have reunited - to record a special version of the hit 1990s sci-fi show's spooky theme tune.

David Duchovny and Gillian Anderson - aka FBI special agents Fox Mulder and Dana Scully - are among the stars to take part in a clip of a new virtual recording of the famous instrumental tune - featuring lyrics for the first time - to raise funds for those in need during the coronavirus pandemic.

Fans who watch the video of the new track, titled Song In The Key Of X, can donate to World Central Kitchen, an organisation that assists communities in crisis.

Fans who watch the video of the new track, titled Song In The Key Of X, can donate to World Central Kitchen, an organisation that assists communities in crisis.

Tweeting the video, Duchovny said: "I know this is silly, and it doesn't feel like a silly time. But I also know we have an energetic, compassionate, loyal and generous fan base who always mobilize to help a great cause."

The X-Files originally ran from 1993 to 2002, following Mulder and Scully as they investigated unsolved cases involving paranormal phenomena.

"The unforgettable theme to The X-Files had no lyrics," the clip begins by saying. "Until now."

Series executive producer Frank Spotnitz came up with the idea to raise funds and challenged X-Files enthusiasts to add the lyrics.

Fans Jennifer Large and Rebecca MacDonald stepped up, and the song has now been recorded by stars including Mitch Pileggi (Walter Skinner), Robert Patrick (John Doggett) and Annabeth Gish (Monica Reyes), as well as Duchovny and Anderson and some of the series' creative team taking part, from their homes.

Mr Spotnitz said he found a "rare opportunity to get The X-Files gang back together", so decided to use it "do something positive" during the pandemic.

It's here. Believe.#XF4WCK #TheXFiles #SongInTheKeyOfX https://t.co/IkirTdbnBu

— Song in the Key of X (@InTheKeyofX) August 21, 2020

"It has been quite an amazing and amusing ride to put together this complex project and we're honoured that so many of our wonderful cast members and team have taken part," he said.

"It's been a real joy to reunite virtually with our friends and former colleagues, and we hope not only to bring a smile to many people, but also to help a worthwhile cause."

The truth - and the new track - is out there now.