Michael’s map

SPOILER ALERT!

Jonas finds a map of the cave system in the roof truss of his family home. But the decisive clue is missing — until the Stranger adds it while Jonas is sleeping. The Stranger sends Jonas a futuristic lamp and a Geiger counter. The map leads him to a metal trapdoor with a mysterious symbol, deep within the Winden Cave. Behind this trapdoor is a shaft that takes Jonas to the year 1986.