Abby and her sister Zara are not real people. They were made, created by pan-dimensional beings – the Grace – to help save space and time.

The Grace gave them special powers. With just a thought they can be anywhere or when in the universe. They can affect people, see into their heads, influence their thoughts.

And they’re still learning what they can do...

For the next 48 hours, you can enjoy a range of savings on the adventures of the Abby and Zara.

The twins first appeared on opposite sides of a struggle for time and space in Key2Time: our first Doctor Who Main Range trilogy!

You can buy all three parts of this Fifth Doctor adventure - Doctor Who: The Judgement of Isskar, Doctor Who: The Destroyer of Delights and Doctor Who: The Chaos Pool, as well the bonus installment Doctor Who: The Companion Chronicles - The Prisoner's Dilema - for just £5 on CD (+p&p) and download.

Then join the twins as they set off to explore the Universe in their very own range - Graceless Series 1, Series 2 and Series 3 are available for just £10 on CD and download.

Special bundles of these titles are also available for futher savings. The two Worlds of Big Finish: The Key2Time bundles gets you all four adventures for just £18 CD or£16 Download - whilst the two  Worlds of Big Finish: Graceless bundles lets you buy all three series for just £25 on CD and Download. Free UK postage applies to both bundles!

The Worlds of Big Finish, a four disc, six episode set, brings together seven heroes to face a threat from beyond the universe. Order now.