Portrayed by Miranda Raison (24: Live Another Day, Spooks, Doctor Who: Daleks in Manhattan), Constance is the no-nosense Chief Wren at Bletchley Park at height of World War II. Able to give the Doctor more than a run for his money, the pair join forces to discover the secrets hidden in encrypted enemy ciphers. But Constance has a few secrets of her own; and it may just take a time-traveller to discover the answers she seeks...

Released as one of several fantastic September releases celebrating Ol' Sixie, Doctor Who: Criss-Cross is the perfect title for listeners new to Big Finish's Sixth Doctor adventuresalong with plenty of surprises for long-term fans!

Check out the trailer for this brilliant new release on the range page here, or by using the SoundCloud player below:

Bletchley Park. Britain's most secret weapon in the Second World War. Inside draughty huts, the earliest computers clatter day and night, decoding enemy transmissions and revealing intelligence crucial to the country's defence. Leading WREN Mrs Constance Clarke directs her charges to provide vital assistance to the boffins stationed in the Manor House. But a recent arrival among the code-breakers, the mysterious Dr Smith, has attracted the attention of MI5's spycatchers...

Over in mainland Europe, Nazi agents are briefed, covert operations planned, and a German submarine embarks on a very secret mission.

As encrypted radio waves criss-cross the planet, unearthly forces stir. And when certain ciphers are cracked, something will emerge to threaten all humanity, regardless of allegiance...

Released in September, Doctor Who: Criss-Cross is a new story by Matt Fitton, and stars Colin Baker, Miranda Raison, Hugh Fraser, Alistair Petrie, Paul Thornley, Charlotte Salt and Robbie Stevens. Pre-order your copy here.

Before her chronological debut, Constance will also appear in Doctor Who: The Sixth Doctor – The Last Adventure – a special four story adventure revealing the secrets of the Doctor's regeneration glimpsed in Time and the Rani. Featuring classic adversary the Valeyard, Jago & Litefoot and three other Sixth Doctor companions, this special set is not to be missed! Click here for more details.