This chapter's title is explained by a quick memory – Louisa, about nine years old, one day starts a conversation with Tom, "I wonder –" to which her father quickly answers, "Louisa, never wonder!" This is Gradgrind's hobbyhorse in a nutshell, obviously, and so much so that he is really stressed about the fact that Coketown has a library – and that workers use that library to read novels about made-up strangers. Yes, clearly he's a few fries short of a Happy Meal. Moving on.
Tom complains to Loo (Louisa) that he really hates everything about his life, and thinks their house is a "Jaundiced Jail." (That's got a nice ring to it, doesn't it?) He tells her that as soon as he can get the heck out of there, he is going to go wild to make up for lost time. Basically, he's going to be a college freshman on a bender.
Louisa worries that Bounderby won't really be into that kind of behavior from one of his employees. Tom laughs and tells her that he's got a trick to handle Bounderby. Ready for it? The trick is Louisa. Since Bounderby has the hots for Louisa, and will probably ask her to marry him, Louisa will have the power to make Bounderby be nice to Tom.
Louisa slow and sadly acquiesces to Tom's demands. She sits and stares at the fire in the fireplace, confessing that she has "unmanageable thoughts that will wonder," at which point her mother comes in to repeat her father's earlier phrase forbidding any wondering of any kind. And you thought your parents don't really get you.