Ep 10. In the Forest of the Night

The Doctor and Clara find themselves in London after waking up to a unusual surprise - the entire city is covered in dense forest overnight, with trees growing everywhere indiscriminately. With no explanation in sight and no idea of how to remove the sudden forest, they cross paths with a young girl named Maebh, who has run away from her foster home due to a disturbing message she received from her little sister. Meanwhile, the Prime Minister and various other officials are growing increasingly concerned with the sudden influx of woodland and are preparing to take action to remove it before it becomes a threat to the populace.

As the trio explore the city and try to figure out what's going on, they come across a series of bizarre and impossible events, like solar flares and tigers appearing in the city, which lead them to believe that something of great cosmic significance is happening. But as the Doctor delves deeper into the mystery, he begins to suspect that the forest is not a menace but actually protecting the planet from something far worse. With time running out and the government preparing to burn the forest to the ground, it's up to the Doctor, Clara, and Maebh to convince the officials that they must spare the trees and work together to avert an even greater disaster that is looming over them all.

The episode is marked by stunning visuals - the forest backdrop is beautiful and haunting in equal measure, and the city's landmarks transformed by the suddenly-appearing flora lend it an eerie, otherworldly quality. The characters are all well-drawn and likable, particularly newcomer Abigail Eames as Maebh, who gives a true-to-life portrayal of a girl struggling with anxiety and fear. There's also a strong environmentalism theme running through the episode, with the Doctor advocating for the importance of preserving nature and its role in maintaining the planet's balance.

Overall, "In the Forest of the Night" is a thought-provoking, visually arresting episode that touches on some big ideas about humanity's relationship with the planet and its place in the universe. With plenty of humor, heart, and intrigue to boot, it's a fresh and engaging installment of the long-running series that is sure to leave fans eagerly anticipating more adventures from the Doctor and Clara.