those impacts. The Doctor hacks into the global cellular network and Maebh reads off a message prepared by the other students to tell everyone on Earth to leave the trees alone, and to request Annabel to come home. Danny tells Clara he wants to know the truth about her travels with the Doctor, and asks her to think about it first. The Doctor and Clara watch the solar flare harmlessly strike Earth from space. As the trees dissipate, the Doctor explains that humanity will forget about the sudden appearance of the trees, as they have before, but the memory will linger as fairy tales. Outside her house, Maebh reunites with Annabel. Continuity The Doctor responds to Clara's suggestion that he save himself and abandon the Earth with her words to him in "Kill the Moon": "This is my world, too. I walk your Earth. I breathe your air". Outside references The title is from the second line of William Blake's The Tyger: Tyger Tyger, burning bright, In the forests of the night. (The forests appear overnight and a tiger appears in the episode). This episode contains many elements of fairy tales, as explained in Doctor Who Extra. For example, Maebh in a red coat getting chased by wolves ("Little Red Riding Hood"). Maebh's last name is Arden, a reference to the forest in William Shakespeare's play As You Like It. Broadcast and reception Overnight viewing figures were estimated at 5.03 million viewers. The episode was watched by a total of 6.92 million viewers. On BBC America this episode was seen by 1.06 million viewers, being the most watched episode since the airing of "Listen". It also received an Appreciation Index of 83. Critical reception The episode received mixed reviews from critics, with some praising its poetic, unique feel and contrasts with the darker episodes of the series, while some were critical of the lack of threat. Ben Lawrence of The Daily Telegraph gave it four stars out of five and called it "powerful". He was positive toward the Doctor's character development and Peter Capaldi's performance. Chris Pyke of Wales Online said the episode was not a "scary or fun adventure", but "languished somewhere in between" and seemed like a filler before the series' conclusion. Matt Dennis of The News Hub criticised the story for the lack of "any real threat or tension for the most part", and described it as