The Chelsea Flower Show - hardly the most exciting or dangerous event in the calendar, or so Doctor thinks. But this is Chelsea 426, a city-sized future colony floating on the clouds of Saturn, and the flowers are much more than they seem.

As the Doctor investigates, a familiar foe arrives, and the stakes suddenly get much higher. The Sontarans have plans of their own, and they're not here to arrange flowers.

Available exclusively on download, look out for The Krillitane Storm and Autonomy with more exclusive unabridged readings to come.