Sasha will have to spend the whole summer in the city: the family does not have money to go to the seaside. But there are more serious troubles in his life. The world around him suddenly became hostile: neighbors looked askance and threw garbage under the apartment door, classmates teased him and called him names, and even his friend Valentina began to shun him... The parents do not explain anything, but are preparing for a hasty departure. The holidays begin a month early for Sasha and his brother Jacob, and the boys, along with their uncle, go to a castle full of secrets, where Nefertiti, Shere Khan and two Napoleons live. And in the attic, where it is strictly forbidden to go up, a mysterious stranger in an iron mask is hiding! The action of the novel by Silene Edgar takes place in 1942 in occupied France. Sasha and his loved ones find themselves in danger, which for the time being he does not even suspect. Over the course of forty-two summer days, which will forever remain in his memory, the boy makes friends, becomes a truly adult and takes responsibility for the fate of those he loves. And he understands: even a boarding house for the insane can become a real island of sanity in the ocean of madness. Silene Edgar (born in 1978) is the author of a dozen books for adults and children, which have received many awards, including the Gulli TV channel award (2014) and Les Incorruptibles ( 2015–2016). The historical story “42 Days” is partly based on real events known to the author from family legends. Her characters are close and understandable to a modern teenager, as if they were our contemporaries. "CompassGuide" opens the work of Silene Edgar to the Russian reader.