Outlander‘s Stephen Walters is unrecognizable in UK-based Channel 5’s new TV thriller that kicked off over the weekend.

The Night Caller, which began airing on Sunday night, tells the story of Tony (Robert Glenister), a down-on-his-luck taxi driver who becomes fixated with late-night radio host Lawrence (Sean Pertwee).

After plucking up the courage to call into Lawrence’s show, Tony becomes a regular caller and “friend of the show”, but his interest quickly turns into an unhealthy obsession.

Stephen takes on the role of Rob, Tony’s workmate and fellow taxi driver.

While Outlander aficionados are accustomed to seeing Stephen as Angus Mhor, complete with long locks, a full beard, and a traditional tam o’ shanter hat, his appearance in The Night Caller is strikingly different.

In the Starz series, he embodies a Highland warrior, but for The Night Caller, Stephen has transformed with a short, neat haircut.

He’s ditched the full beard for this role, sporting only a thick moustache.

Discussing his character with Channel 5, Stephen said: “Rob is an ex-military man, he served in Afghanistan and now works as a taxi driver, which is how he knows Tony.”

“We find out that Rob is a drug addict and possibly suffers from mental health issues too.”

The four-part drama will air consecutive episodes each night until its conclusion on Wednesday, July 10.

Viewers will delve deeper into Rob’s past with Tony as The Night Caller tackles themes of loneliness and depression.

Stephen openly discussed a personal link to the series’ themes, stating: “Sadly, a friend of mine took his own life recently and I had no idea he was suffering or had mental health issues.”

“He didn’t seem lonely to me, but he was. So it’s important the way this drama explores those areas the fragility of the human mindset and loneliness.”

“Being lonely shouldn’t be taboo and should be spoken about, I think it’s getting better, but we still need to raise awareness of it, it shouldn’t be anything to be embarrassed or ashamed about.”