The first title in the GUARDIANS OF SLEEP series. It's close to the end of term, and Serena is having nightmares. Beneath what her parents assume to be nerves at the upcoming exams, something more sinister is concealed. A character who introduces himself as Doctor Lethargy, the father of her classmate Insomnia, threatens Serena and her friends Virginia, Rául and Simón. The four realise something is up when their dreams start having consequences in real life...