When memories lie, the truth can be fatal.

In the aftermath of an improbable mission, the Fugitive Doctor and Martha realise that something is interfering with their minds. Something that doesn't want to be found.

Their investigation leads to a curious artefact in the British Museum: an apparently medieval toy known as the Kaleidoscope. But the object refuses to stay in one place, one time - or one identity. And when the Doctor is repeatedly mistaken for someone she's never met, fragments of unfamiliar memories begin to surface.

Across the Earth, a hidden pattern emerges; evidence of a secret that someone has gone to extraordinary lengths to conceal. As ancient enemies close in and innocent lives are put at risk, the Doctor learns the hard way that some truths were buried for a reason...

A key instalment of the Doctor Who transmedia event Circuit Breaker, this novel is written by the Fugitive Doctor herself, Jo Martin - and also features Martha Jones (as played by Freema Agyeman) together with the Unified Intelligence Taskforce, or UNIT.