The Doctor lands in London this week, but gets the shock of his life when he opens the doors of the TARDIS to discover Trafalgar Square is now engulfed by a massive forest!

As the bemused Time Lord investigates further it soon becomes clear that our capital isn’t the only place to be swallowed up by a sea of plants and trees over night. In fact, the entire planet is covered in vegetation!

Meanwhile, a few miles away, Clara, her schoolteacher boyfriend Danny Pink and his class of schoolkids are equally shocked when they emerge from a visit to the Natural History Museum to find themselves in the middle of a dense forest, too.

Yet Clara and Danny have a bigger problem because one of the pupils, Maebh has gone missing!

After hearing mysterious voices, young Maebh flees into the forest and stumbles upon the TARDIS, where the Doctor struggling to make sense of his surroundings. He asks Maebh stay out of trouble inside the TARDIS ,but after catching a glimpse of one of her school books he suddenly realises with horror that the trees have come to destroy Earth and Maebh holds the key to mankind’s survival!

After centuries of mistreatment at the hands of humans, the trees are exacting their revenge and worse still, it seems a massive fireball is on its way to incinerate everthing! Can Clara, Danny and the schoolchildren help the Doctor save the human race from certain destruction?