Emma Nightingale is a relentlessly practical, logical single mother raising a highly imaginative son. Emma does not read fiction or poetry or go to the movies; Rupert loves his Donald Duck comics, draws fantasy creatures, and tells wildly imaginative stories. Emma feels this is dangerous, but there's a limit to what she can do about it.
She also doesn't understand his enthusiasm for trains, but it's something he shares with his father, so she tolerates that for the sake of the father/son relationship.
But one day Rupert and his father Gunnar come home from their expedition very upset. Rupert says that a train tried to kill them, and says confusing things about trains that don't keep the timetables and can leave the tracks.
Later that day, on his way home, Gunnar is killed when a train track guard arm is up when it should be down, and Gunnar's car is on the tracks when the train comes.
Emma spends the next few years trying to eliminate all of the dangerous, upsetting imagination and fantasy from her son's life, for his own safety. For a long time, it seems she has succeeded. Then trains come back into their lives, in a shocking way, and Emma and Rupert are on their way to an even more startling resolution of a conflict with an enemy Emma can barely imagine.
The writing here is extremely effective, and Jääskeläinen draws us in to a character who initially seems very unsympathetic to anyone who would be reading fiction, never mind fantasy. Emma proves to be more complex and interesting than initially apparent, and what Jääskeläinen is doing with time and reality is thoroughly fascinating and satisfying.