"Gemina" is the second book in the Illuminae Files series, written by Amie Kaufman and Jay Kristoff. It continues the story of a space colony called Heavenly, which is under attack by a mysterious enemy. The narrative is presented through a mix of documents, chat logs, and illustrations, creating a unique reading experience. The main characters, Hanna and Nik, must work together to survive the invasion and uncover the truth behind the attack. As they navigate danger and betrayal, they also explore themes of friendship, loyalty, and the consequences of war.