Trains are powerful symbols for motion. Ever since the Industrial Revolution, trains have been moving people and cargo across the world. But The Girl on the Train is more like The Little Engine that Couldn't. The "girl" might be on the train, but she's just sitting there, stewing, watching other people who themselves are sitting there, stewing. For a book structured around a train, it sure is filled with people going nowhere.
Questions About Inertia
Which characters grow and/or change during the novel, and which stay the same? What patterns do you notice and what do they reveal about inertia as a theme in this book?
If Rachel gets on a train every day, why the heck doesn't she go somewhere instead of just going back and forth to an imaginary job?
Megan isn't happy in her marriage, and she dreams of running away. Why doesn't she leave her husband? What is holding her back?
Chew on This
Both Megan and Rachel are stuck between unhappy pasts and uncertain futures. Instead of moving forward into uncertainty, though, they dwell on the pasts they can't change.
Tom is another character who is stuck, but stuck in his behavioral patterns. He has lied himself into a hole, and he can only move from one gullible wife to the next, a lateral promotion for sure.