The Unified Intelligence Taskforce – an international initiative to investigate and confront alien attacks across the planet Earth. From a secret headquarters in the Tower of London, the UK division is led by Kate Stewart (Jemma Redgrave) - the daughter of the legendary Brigadier Lethbridge-Stewart - an expert in combating the extra-terrestrial threats that seek to conquer the world.

UNIT's latest threat comes in the form of the terrifying Tengobushi, a mysterious caste of alien warriors, whose reasons for arriving on Earth are linked to a dangerous new initiative. Listen to the trailer below:

2.1 Power Cell by Matt Fitton

Osgood and Captain Josh Carter are sent to investigate the disappearance of a UNIT scientist.

Meanwhile, alien technology has fallen into the hands of Lyme Industries, and Kate Stewart can't persuade the company’s CEO, Felicity Lyme, to give it back.

But UNIT find themselves fighting a third battle when innocent people start to die. Who are the mysterious assassins? And what does Felicity Lyme want with top secret alien technology?

2.2 Death in Geneva by Andrew Smith

With few people left to trust, and with assassins on their tail, Kate and Osgood race to UNIT Command in Geneva. Will General Blair be able to help them?

But when death follows UNIT all the way from the English countryside to the snowy slopes of the Alps, Captain Carter finds himself in a race against time.

As the body count rises, Kate struggles to separate friend from foe, danger circles Osgood ever closer, and, high in the mountains, Josh comes face to face with the enemy...

2.3 The Battle of the Tower by Andrew Smith

The threat is now clear, and Kate Stewart retreats to UNIT HQ with her most trusted colleagues. She has no choice but to place the Black Archive into lockdown, and the Tower of London is where UNIT will make its stand.

While the capital sleeps, an alien horde is gathering, ready to rise from the shadows to attack Earth’s greatest defence force inside its own stronghold.

The Tower is infiltrated, and UNIT must hold the line. At any cost. Lock and load...

2.4 Ice Station Alpha by Matt Fitton

Caught between human greed and an unstoppable alien power, Kate Stewart leads her closest allies on one final, desperate mission. This could be the very last chance for the human race.

But the UNIT team has been declared rogue, and ruthless military forces are in pursuit as they race across the globe. Kate calls Lieutenant Sam Bishop to their aid, while Josh and Osgood head out across the frozen Antarctic plains to try and prevent a disaster no-one else knows is coming.

Big Finish proudly present Jemma Redgrave, Ingrid Oliver, Warren Brown, James Joyce, Alice Krige, Asif Khan, Tyrone Huggins, Nigel Carrington, Beth Chalmers, Harry Ditson, Dan Li, Akira Koieyama, Stephen Billington and Jot Davies in UNIT: Shutdown, available to buy now for £20 on CD or to download!

You can also order the set as part of the UNIT: The New Series bundle, alongside 2015's UNIT: Extinction, November's UNIT: Silenced and a fourth box-set due for release in 2017. With complimentary digital copies included with CD orders, you'll be able to enjoy the new missions as soon as the box-set is deployed! Listen on the go with the official Big Finish Player app, available on iOS devices now.

Check out Big Finish's full range of audios based on the New Series of Doctor Who on our range page here.