The eBook is written by Malorie Blackman, author of the Noughts & Crosses series and Pig Heart Boy, and features the Seventh Doctor and his companion Ace, played in the TV series by Sylvester McCoy and Sophie Aldred respectively.
A synopsis has been released for the story:
When the TARDIS lands on Skaro, the Seventh Doctor and Ace are shocked to discover the planet has become the universal centre of learning, populated by a race of peace-loving Daleks. Ever suspicious of his arch enemies’ motives, the Doctor learns of a threat that could literally tear the universe apart…The eBook will be released on 23rd July, and will cost £1.99. The Ripple Effect, alongside the ten other eShorts published throughout the year, will be included in a paperback anthology released on 23rd November.
[Source: Doctor Who TV]