THE fourth novel of a Welsh crime series follows the disappearance of a girl from Conwy and a race against time to track her down.

Lost Souls sees the return of detective Gaby Darin as 10-year-old Ellie Fry goes missing from her home in Colwyn Bay. There is no reason for her to run away and soon the police are on the chase. There has been a spotting on the Great Orme - and then nothing.

At the same time there is a problem at the local crematorium with the discovery of three prosthetic hip replacements found amongst the ashes when there should have only been two at most. Two separate cases, which have Gaby and her team running around in circles until an old woman disappears in Conwy. Could all of these incidents be linked?

"With Lost Souls I wanted to create the feeling of a road trip across North Wales as Ellie tries to escape detection," said Jenny O'Brien, who used to live in Llandudno.

"She heads out with troubled youth, Ronan Stevens, from Colwyn Bay to Llandudno and finally stopping in Caernarfon where they walk from the train station to an isolated farmhouse in Dinas Dinlle. We took the children there a few years ago and writing that walk brought back very happy memories of a beautiful area."

All of Mrs O'Brien's books are set in Wales - the first, Silent Cry, is located St David’s in Pembrokeshire, while books two and three, Darkest Night and Fallen Angel, are set in North Wales.

Each book can be read as a standalone but the central thread is Detective Gaby Darin and her team.

"As a character she’s short and round with a tendency to say what she thinks, which makes her great fun to write," said Mrs O'Brien. "In Lost Souls she’s settling down into a routine following a traumatic book one and two and a harrowing book three. The books are all set in a narrow timeframe with barely pause for breath between cases.

"Gaby can’t believe that a week following the last case she’s again in the thick of a crime scene when all she wants is a break to catch up with the paperwork. I see Lost Souls primarily about relationships. Ellie’s relationship with troubled Ronin. Gaby’s relationship with her team and, finally, Gaby’s difficult friendship with acerbic pathologist, Rusty Mulholland."

Mrs O'Brien's last novel, Fallen Angel, saw detective Darin face a professional and personal battle during a murder investigation after a handmade dress is found on the Great Orme.

The Dublin-based author previously said: "Llandudno still holds a special place for me. Visits to the Great Orme were a treat and I have glorious memories.

"Looking back through the lens of childhood, things seemed brighter and better."

Lost Souls was published by HQ Digital/Harper Collins in eBook format last week and will be available in both paperback and audio in July.