December's Books on Screen roundup includes the feature films Mortal Engines, Spider-Man: Into the Spider-Verse, Mary Poppins Returns and Aquaman; the film release of Mowgli: Legend of the Jungle and the debut of "Watership Down" on Netflix; the ongoing series "Black Lightning," "The Flash" and "Arrow" on The CW; and the DVD releases of The Miseducation of Cameron Post, I Still See You, Unbroken: Path to Redemption, The House with a Clock in its Walls, Venom, Little Women.