Tracy Ann Oberman is to front a brand new audio play based on Doctor Who spin-off show Torchwood.

Back in 2006, Oberman guest-starred in the two-part Doctor Who television story, Army of Ghosts / Doomsday as Yvonne Hartman: head of Torchwood One slap bang in the middle of Canary Wharf as it found itself slap bang in the middle of a double whammy attack from Cybermen and Daleks.

It’s no secret to say – spoiler alert – that Hartman didn’t make it out of that one alive. Sort of. Yvonne was given a forced Cyber-conversion, but her personality reasserted itself and in her new steel form she managed to help save the day.

Now Big Finish – producers of hundreds of Doctor Who related audio productions since 1999 – have turned back time and set an episode of their new Torchwood series in the months prior to Yvonne’s demise, as the character makes a trip to Cardiff on 26th March 2005 – the day that everything changes.

In One Rule, it’s been three weeks since the Mayor of Cardiff was killed by a shop dummy and the fight is on to see who will replace him. Hartman is in town to retrieve an invaluable alien device, but finds herself caught up in that fight, as a bloodthirsty alien stalks the streets, and there’s a special offer on at the all-you-can-eat Chinese buffet.

Written by former Torchwood and The Sarah Jane Adventures scribe Joseph Lidster, and directed by the king of all Dalek operators, Barnaby Edwards, the play also features Doctor Who veterans Gareth Armstrong, Dan Starkey and Cartin Stewart, and former Doctors star Rebecca Lacey.

The story is the fourth in the series which also sees the return of John Barrowman, Gareth David Lloyd, Eve Myles and Kai Owen to their regular roles as Captain Jack Harkness, Ianto Jones, Gwen Cooper and Rhys Williams across the previous instalments.

One Rule is released in December, and is available to pre-order on cd and download from Big Finish now.