The Client; by John Grisham.

A little boy who is older by far than his years, helper and often protector of not only his little brother but his mother as well, since she is separated and trying very hard to bring up her children with right values. They are just playing in woods, when a large car drives into their private nook of the world and the adult male proceeds to attempt suicide.

Sneaking away as any other child might have done might have avoided all further trouble, who knows? But this child, good at heart and brave too, will try to stop the man from dying, and in the process get embroiled in deep morass - only, fortunately, when it comes to it he is able to find a lawyer practically tailor made for him, an elderly woman who knows the world as it can be and helps.

It is the client that takes the lead, though, at more than one stage, and finally they are able to bring justice in after a blood curdling adventure.”