"I think theatres need to tell more stories," says Rosemary Leach, and that's exactly what The Shell Seekers, in which she stars as a nostalgic matriarch, has set out to do.

An adaptation of Rosamunde Pilcher's 1987 novel, a modern classic which has sold over 5 million copies, this is a touching family saga about the secrets, passions and heartbreak which span three generations.

Like many subsequent best-sellers, at the heart of this story is a mysterious painting. But, unlike Tracy Chevalier's Girl With A Pearl Earing or Dan Brown's The Da Vinci Code, Pilcher imagined the oil painting of The Shell Seekers as well as its legacy.

Following a heart attack, Penelope Keeling discharges herself from hospital and returns to her grand house in Cornwall. She intends to take time to look back on her life, enjoy time in her home and take comfort in her prize possession - a painting done by her father, Lawrence Stern, during the Second World War.

Penelope's children - Nancy, a prim housewife, Olivia, an ambitious magazine editor and Noel, a scheming entrepeneur - have other ideas.

Having read in the paper about a Sotheby's valuation of a Lawrence Stern, they have started to take a new interest in the well-being of their fading mother, while keeping a watchful eye on the canvas of The Shell Seekers.

"Penelope is in the process of organising her life and preparing for the day she will no longer be in this world," says Leach, who played the lead in the BBC's Cider With Rosie and was nominated for a Bafta for her role as Helena Bonham Carter's mother in Room With A View.

"In an attempt to sort out her present by reviewing the past, she goes back to 1939, to her memories of Cornwall, her parents and her secret wartime love. It's a story about family, parental love and a love of place."

Adapted by the husband and wife team of Terence Brady and Charlotte Bingham, whose television credits include Upstairs Downstairs, The Shell Seekers has been playing to sell-out houses on this national tour.

Under the name of Jane Fraser, Rosamunde Pilcher also wrote for Mills And Boon , and you can expect a decent helping of dashing gardeners, valiant soldiers and innocent young girls - but the world of gentle romance is experienced here through the ache of the past.

"People have a personal resonance with what happens in the end," Leach says. "It is not a sad story but it is very moving, and people can see something of themselves in the drama which unfolds."

Starts 7.30pm, Wed & Sat mats 2pm, Tickets £15-£23, Call 01903 206206