'They've reopened the X-Files': David Duchovny and Gillian Anderson reunite Mulder and Scully after 14 years to face a new threat from an old enemy

David Duchovny and Gillian Anderson slipped into their old roles of Fox Mulder and Dana Scully for the first time in 14 years on Sunday night, as the X-Files reboot had its premiere.

Bursting back onto TV screens that saw them film 202 episodes across nine seasons, the Hollywood duo were reunited as they once again plunged headlong into the paranormal. 

It was same old Mulder spouting conspiracy theories while same old Scully tried to keep him in check - but with only six episodes to play with former agent Dana was already a believer by the end of the night.

I want to believe: David Duchovny and Gillian Anderson reunited Mulder and Scully after 14 years to face a new threat from an old enemy as the X-Files returned on Sunday night

The episode opened with Fox recapping his fantastical beliefs in his signature deadpan monotone.

'In 2002 the government closed the X-Files... but my personal obsession did not,' he droned. 'We must ask ourselves are they really a hoax? Are we truly alone? Or are we being lied to?'

Fans were then bathed in a warm flood of nostalgia as the unaltered title sequence kicked in, complete with Mark Snow's unchanged iconic theme tune.

Remember this? Fans were bathed in a warm flood of nostalgia as the unaltered title sequence kicked in, complete with Mark Snow's unchanged iconic theme tune

Gross! The episode opened with Fox recapping his fantastical beliefs in his signature deadpan monotone, featuring some creepy snaps from the original X-Files

The show then jumps back to 1947 and the site of the supposed Roswell crash - which is shown to be very much fact.

As an unnamed doctor is escorted by military to the wreckage of an alien ship, they find an injured alien crawling away; the doctor is appalled when the soldiers open fire and kill it.

It then jumps ahead almost 70 years to today, where Scully, now working as a surgeon, gets a call from her former boss Skinner, who is trying to track down her former partner, who we find holed away and sporting some serious stubble.

The truth is out there: The show then jumps back to 1947 and the site of the supposed Roswell crash - which is shown to be very much fact

Witness: As an unnamed doctor is escorted by military to the wreckage of an alien ship

Welcome to Earth: They find an injured alien trying to crawl away from the wreckage 

Ask questions later: But the soldiers open fire, killing it

He wants him to meet with a wealthy and successful conspiracy theorist Tad O'Malley - played by Joel McHale - who takes them to meet a young women named Sveta, who claims to have been abducted several times and had fetuses stolen from her... with the scars to prove it.

The girl, whom Mulder interviewed as a child after her first encounter, claims to be psychic and telepathic, and even posses alien DNA; indeed she knows Mulder and Scully had been in a relationship and even had a baby together. But Scully, ever the skeptic, asks to test her DNA.

Meanwhile O'Malley flies Mulder to a secret research facility where a team of scientists unveil an ARV - or alien reproduction vehicle - a spacecraft supposedly reverse-engineered from extra-terrestrial technology.

Today: It then jumps ahead almost 70 years to today, where Scully, now working as a surgeon, gets a call from her former boss Skinner, who is trying to track down her former partner, who we find holed away and sporting some serious stubble

Soup to Champagne: Skinner wants them to meet with a wealthy and successful conspiracy theorist Tad O'Malley - played by Joel McHale

Chemsitry: The quietly paranoid Mulder and the no-nonsense Scully have not changed a bit

The ship is then shown levitating, before disappearing completely, right before Mulder's eyes.

The scientist confirms it is powered by 'Ununpentium', or Element 115, something the government have had possession of since the 1940s, but, as Mulder theorizes, kept secret while energy companies made billions of dollars.

'Essentially the energy of the universe: no fuel, no flame, no combustion... all electro-magnetic,' the scientist confirms.

Taken: O'Malley takes them to meet a young women named Sveta, who claims to have been abducted several times

Ouch: She claims she had fetuses stolen from her... with the scars to prove it

Grim: Sveta said she had false memories implanted, but still could recall having babies taken from her

Mulder then returns to FBI headquarters to check physical X-Files to find that - while his I want To Believe poster is still there and his pencils are still stuck in the ceiling - the files themselves have been removed.

He then meets with the doctor from the Roswell crash site - now an old man - who encourages him to keep digging, but worries they will be scorned if they bring their knowledge public.

Mulder, Sveta and O'Malley then attempt to convince Scully of their theory: that alien technology is real, and that an invasion is impending... but not by the aliens themselves.

Nice ride: Mulder is then taken to a secret research facility where a team of scientists unveil an ARV - or alien reproduction vehicle - a spacecraft supposedly reverse-engineered from extra-terrestrial technology

I'm a believer: The ship is then shown levitating, before disappearing completely, right before Mulder's eyes

'Alien technology being used against us, not by aliens, not with aliens but by conspiracy of men against humanity,' Mulder claims.

He tells her aliens were attracted to Earth by mankind's discovery of the H-bomb, as they tried to prevent us from bringing extinction upon ourselves.

But the government began using the technology to abduct humans, attempting to breed hybrids using alien DNA.

Old job: Mulder then returns to FBI headquarters to meet Skinner and check physical X-Files, only to find that the files themselves have been removed

Relics: However his I want To Believe poster was still there, and his pencils were still stuck in the ceiling 

Crackpot? O'Malley believes a group of elites are using alien technology and plan on taking over the world

Mulder and O'Malley claim a group of elites are now using everything from induced drought, consumerism, pharmaceuticals, the militarization of the police and the Patriot Act to wrest control of the US and then the world, under the guise of attacks by terrorists or even aliens, and that they plan to tell the world via O'Malley's webcast the following day.

But Scully is not convinced, telling them their 'fearmongering and technophobia is so stupid and incredibly responsible, it borders on treason', before also informing them Sveta's DNA did not reveal anything alien about it.

But the following day, Sveta appears to recount her support of O'Malley, telling news crews he paid her to make everything up, while O'Malley's webcast is shut down.

On board? Mulder believes O'Malley, and tries to convince the skeptical Scully

Mercy mission: He tells her aliens were attracted to Earth by mankind's discovery of the H-bomb, as they tried to prevent us from bringing extinction upon ourselves

Rid of the evidence: Unbeknownst to any of them, a heavily armed group descends on the hidden research facility and blows up the ARV, killing all the scientists

Bad news? Scully receives the results of Sveta's blood test, as well as her own, which seems to confirm her suspicion both of them have alien DNA

At that same time, unbeknownst to any of them, a heavily armed group descends on the hidden research facility and blows up the ARV, killing all the scientists.

Scully then receives the results of a retest of Sveta's DNA, as well as her own which she had tested alongside on a hunch, which finally clicks it into place for her. 

'I sequenced her entire genome. She's not the only one,' she tells Mulder, apparently confirming she too has alien DNA.'Someone needs to stop these sons of bitches.'

Changing her tune: Sveta appears to recount her support of O'Malley, telling news crews he paid her to make everything up, while O'Malley's webcast is shut down

Race is on: Mulder and Scully decide they must find and protect Sveta, who they believe had been coerced into changing her story, and has now disappeared

Uh-oh: However Sveta, fleeing through the desert in her car, finds it suddenly dies, before she is enveloped in light

Elaborate: she looks up to see an alien craft, which targets her with a green beam of light, blowing up the car before she can escape

They then decide they must find and protect Sveta, who they believe had been coerced into changing her story, and has now disappeared.

However Sveta, fleeing through the desert in her car, finds it suddenly dies, before she is enveloped in light; she looks up to see an alien craft, which targets her with a green beam of light, blowing up the car before she can escape.

The final scene shows Mulder and Scully's old nemesis, the Cigarette-Smoking Man, as he takes a drag through a hole in his throat and tells someone off screen: 'We have a small problem - they've reopened the X-Files.

The second part of the two-part premier takes place on Monday night. 

Still going: The final scene shows Mulder and Scully's old nemesis, the Cigarette-Smoking Man, as he takes a drag through a hole in his throat, remarking: 'We have a small problem - they've reopened the X-Files

The return of the show comes 14 years after the last episode of the X Files aired on TV, which saw a dramatic finale where Mulder and Scully were forced to fight to keep their secret roles - and the very existence of the supernatural - under wraps.

The X Files first aired in 1993, and told the story of FBI special agents Mulder and Scully, who were tasked with Investigating X Files: marginalized, unsolved cases involving paranormal phenomena.

Created by Chris Carter, David and Gillian were handed roles of a lifetime, which saw them propelled to global fame.

Spanning nine series and two feature films (1998's The X Files and 2008's The X Files: I Want to Believe), the two leads have revealed it took them a long time to appreciate what their breakout roles gave them.

Blast from the past: The X Files first aired in 1993, and told the story of FBI special agents Mulder and Scully, who were tasked with Investigating X Files: marginalized, unsolved cases involving paranormal phenomena

Roles to be remembered: Created by Chris Carter, David and Gillian were handed roles of a lifetime, which saw them propelled to global fame as the secretive duo

Speaking ahead of the launch of the tenth series, during the Fox TCA Panel earlier this month, Gillian candidly revealed ill-feelings about her long-standing role initially clouded her mind.

She explained: 'It took me a long time to embrace it [her role as Scully] after we were done with the series.

'It took a good decade for me to start thinking of it as the gift that it was and appreciate the opportunity I had and how fortunate I was to play a great, iconic character in a show that was iconic in itself.'

Explaining how they both needed a break to move away from the show and gain a positive perspective, David said: 'It took awhile to recognize it as the gift that it is, and that's why we're able to come back now.'

And in the latest six episode offering of the beloved sci-fi drama, fans can expect a mix of old and new cases, as well as some familiar faces.

'We do have a funny one, a horror one, a gross, nasty one, and three that are extending and elaborating and negating in some ways the old mythology,' David teased prior to the premiere. 

'It took me a long time to embrace it': Speaking ahead of the launch of the tenth series, Gillian candidly revealed ill-feelings about her long-standing role initially clouded her mind

'It took awhile to recognize it as the gift that it is, and that's why we're able to come back now': David and his co-star revealed the near 14 year break from the iconic roles was the reason they were able to come back to it

Back to para-normal: In the latest six episode offering of the beloved sci-fi drama, fans can expect a mix of old and new cases, as well as some familiar faces

And during a 20-minute preview called The X Files: Re-Opened, part of the new plot was revealed to specifically concern Mulder and Scully's son, whom they gave up for adoption. 

'I can't help but think of him, Fox,' Dana Scully says in the preview clip.

'He'd be 15 years old now. I've missed every single year of his life and sometimes I hate myself that I didn't have the courage to stand by him.' 

And as well as Gillian and David, the cast for the new season includes Mitch Pileggi, Annabeth Gish, William B. Davis, The Lone Gunmen trio (Richard "Ringo" Langly, Melvin Frohike and John Fitzgerald Byers); as well as newcomers Annet Mahendru, Joel McHale, and Lauren Ambrose.

But fans should not expect another season quite yet, as David revealed his and Gillian's schedules are looking fully booked till 2023.

'Gillian and I have talked about that, and then we just stop because we get to 2023 and we still haven't found a date we can do it,' the Holy Cow author said.

'It's like, "Let's just wait and see what happens after this," and then we can start to talk seriously about whether we can make it work again.'

Old and new: The cast for the new season includes Mitch Pileggi, Annabeth Gish, William B. Davis, The Lone Gunmen trio; as well as newcomers Annet Mahendru, Joel McHale, and Lauren Ambrose