Sheridan Smith thriller The Castaways comes to Channel 5

​The thought of being marooned on a deserted island is some people’s worst nightmare.

And while filming five-part survival drama The Castaways, some of actress Sheridan Smith’s own fears became reality.

Speaking to Digital Spy before the show’s original release on Paramount+ in late 2023, Smith said. “I was terrified of water and I’m in water for most of the show.

“And I’m scared of heights and I was up a tree and on a cliff so it was a challenge.

“But I like a challenge. And I was in safe hands, so I’m really pleased I took it and we got to film in Greece for six weeks. How amazing.”

The actress, who won a Bafta for her role in Mrs Biggs in 2013 and an NTA for Cilla two years later, went on to describe the intense training she had to undergo ahead of filming the Lost-style show.

“I had a few sessions with the stunt guys, first in a swimming pool then in the sea,” she says.

“I couldn’t even go underwater without holding my nose. They had to keep putting me in the shallow end. But I did get braver.

“The stunt team was amazing. They were always nearby, so if I had to dive out of my depth, knowing that I couldn’t swim, then they’d be nearby to grab me when I came up.”

Adapted from Lucy Clarke’s best-selling novel, The Castaways begins tonight and continues every evening until Thursday.

It follows sisters Lori (Smith) and Erin (Celine Buckens), who treat themselves to an all-inclusive holiday of a lifetime to Fiji in an effort to spend some quality time together.

After a dramatic argument – the details of which become clear over the course of the show – Erin never boards the propellor plane to the second resort.

However, the aircraft, with Lori on board, fails to arrive at its island destination.

Months later, after an investigation concludes that the plane plummeted into the middle of the ocean with no survivors, Erin is convinced that her sister is still alive.

When Lori’s credit card is suddenly used in a corner shop in a remote village in Fiji by the plane’s pilot (Brendan Cowell), whom Erin recognises from CCTV footage, it appears she may right.

Although Lori’s husband and pregnant new girlfriend remain uninterested in the development, Erin flies to the island to unpick the mystery of her sister’s disappearance.

Flitting between the two sisters’ perspectives, we see the events leading up to the plane crash, and Lori’s subsequent struggle for survival alongside her motley crew of fellow castaways.

Meanwhile, Erin’s credibility is also called into question as it becomes clear she hasn’t been completely truthful about what she knows.

Despite the challenging filming process, Lincolnshire-born Smith, 43, says she really enjoyed the project, her time on the ‘desert island’ and overcoming her fears.

“I’m used to playing cardigan-wearing mums up north somewhere,” she says.

“I definitely would love to do more of this genre. If I get cast. We’ll see how it goes.”