IF you haven't watched last Tuesday's episode of River City, then look away now. Spoilers lie this way. Still here? Well, you have been warned …

It's a wintry February morning in Glasgow and over coffee Kathryn Howden is discussing the heart-wrenching storyline that has seen her TV soap character Maggie McLean reveal she had been a victim of rape and incest.

Viewers saw Maggie confess the dark secret to daughter Caitlin, who learns on her wedding day that the man she thought was her uncle is in fact her biological father.

Kathryn, 56, approached the role with considered care. "I felt a huge responsibility," she says. "Particularly if people have been through that same kind of thing. As an actor you want to do it as truthfully as possible. I was trying to think how I would feel if it was me."

Not least imagining the burden of keeping the truth hidden for all those years. "Maggie hadn't told anyone," says Kathryn. "He is her brother and that, I think, is the most difficult thing. It is family and that must be awful on so many levels."

While the scenes were being shot, Kathryn was dealing with personal tragedy in her own life. Her mother, Freda, was gravely ill and passed away in early November. The Edinburgh-born actress channelled that grief into her on-screen performance.

"I was rawer than I would normally have been," she reflects. "It helped with the emotions always being there and what I did was focus it in on the storyline."

River City fans will witness the aftershocks continue to reverberate through Shieldinch in the latest instalment tonight. "I don't think that you can expect everything to go back to being happy families again," says Kathryn. "It is going to take a long time."

It marks new territory for Kathryn who has spent much of her career in theatre and is well-known to theatre audiences across Scotland from the Traverse to the Tron.

A self-described "shy middle child of three", Kathryn was born in Leith and grew up in the Pennywell area of Edinburgh. "My mum was delighted because we had a toilet, underfloor heating and two bedrooms after living in a room and kitchen in Leith," she says.

Joy lights up her face as she recounts an unconventional and often quirky upbringing. "We thought our childhood was absolutely normal, but it was actually quite mad," says Kathryn. "Whenever people asked: 'Are you working class?' I never used to know what to say. My dad didn't work 9-5."

Her father Alex "Happy" Howden, as he was nicknamed, was a colourful character and regular on the stand-up circuit. After leaving school at 15, he had variously worked as a miner, scaffolder, whaler and bus driver while trying to break into comedy.

The tales of his antics are unbounded. While working as a bus driver he was known to stop mid-route, leaving the passengers on board, to squeeze in a 20-minute open mic slot at the local social club. "He would say: 'Just nipping into the loo, ladies …'" chuckles Kathryn.

A love of performing is clearly in the genes. Kathryn and her elder brother Lewis both cut their teeth at Edinburgh Youth Theatre before going on to study at the Royal Scottish Academy of Music and Drama, now the Royal Conservatoire of Scotland, in Glasgow.

While filming the BBC drama Looking After Jo Jo – a gangland thriller set in 1980s Edinburgh with Robert Carlyle in the lead role – Kathryn met and fell in love with fellow actor Gilly Gilchrist. That was 1997. The couple have been together ever since.

The universe has its grand plan and it was perhaps serendipity they would end up together. Kathryn and Gilly grew up just a stone's throw away from each other in Pennywell and Pilton – and unbeknownst to the pair until many years later had even lived in the same Leith street as babies.

These days they live in Glasgow with their 13-year-old daughter Holly. While Kathryn regularly treads the boards in theatre, Gilly can be found gracing our TV screens in dramas such as The Replacement, Rillington Place and In Plain Sight.

"He has just finished on Outlaw King," says Kathryn. "Oh, I did a wee day on that too – my day with Chris Pine. It was the very first day of filming and the whole day was just Chris Pine and me. Unfortunately, I was this woman from the woods, looking manky ..."

What was Chris Pine like? There's a twinkle in her eye. "He was lovely." The David Mackenzie-directed film about Robert the Bruce is scheduled for release on Netflix this autumn.

When it comes to future ambitions, Kathryn quite fancies trying her hand at directing. There is a long list of stage roles she is keen to tackle, but for the time being is looking forward to seeing where her adventures on River City will lead.

She is clearly enjoying being part of the BBC Scotland series which she joined in late 2016. Kathryn has forged a close bond with Gayle Telfer-Stevens and Leah MacRae who play her on-screen daughters Caitlin and Ellie.

"Och, it's amazing," she says. "When I came in to the show, I wasn't sure what it would be like. It's that thing where you go into anything new and think: 'Is it going to be cliquey? Will I feel like an outsider?' But from the first day it felt like family."

River City is on BBC One, tonight, 8pm. Thanks to Clockwise, Savoy Tower, 77 Renfrew Street, Glasgow (workclockwise.co.uk)