Doctor Who: The End of the Beginning

The Universe is in a state of crisis, facing destruction from the results of a strange spatio-temporal event. And the Doctor is involved in three different incarnations - each caught up in a deadly adventure, scattered across time and space. The whole of creation is threatened - and someone is hunting the Doctor. The three incarnations of the Doctor must join together to confront their implacable pursuer - but in doing so will they unleash a still greater threat?