Vortex Ice / Cortex Fire is one of three main range 2017 Doctor Who titles consisting of two two-part stories, in a change from the usual four-parters. Vortex Ice by Jonathan Morris. In search of 'exotic particles', the Doctor and Flip arrive 700 feet underground, in a mine in Northern Mexico - only to run into a scientific expedition. Among their number, an exobiologist. They're all on the hunt for alien life! Deep underground, the team finally uncovers a cave of vast crystals - like ice, despite the heat. And inside the crystal: something frozen. Something trapped in time. If only it were something simple, like a monster. But it's far, far worse than that. Cortex Fire by Ian Potter. The Doctor brings Flip to the futuristic city of Festin, the best vantage point to witness a unique astronomical light show. In a city governed by the all-powerful network known as the Cortex, they're soon identified as outsiders - nihilists, perhaps, responsible for a wave of terror that's been sweeping the city...But the truth is different. The people of Festin are burning up. Spontaneously combusting. And no-one knows why. Star Colin Baker played the Doctor on television between 1984 and 1986, and has found a new legion of fans through his work with Big Finish. Lisa Greenwood plays companion Phillipa Flip Jackson, and will be familiar to some from TV shows such as Call The Midwife, The Hours and Eastenders. CAST: Colin Baker (The Doctor), Lisa Greenwood (Flip Jackson), Shobu Kapoor (Sai Chopra), Orlando Seale (Dylan Argent), Monty D'Inverno (Jannik Woolf), Rebecca Todd (Khoralla), Simon Kane (Halus), Eve Webster (Bav/ Cortex/ Enforcer).