The Firm
Let's get things started with what I consider a no-brainer: The Firm.
This book, released in February 1991, covers the tale of Mitch McDeere and his wooing by a prestigious Memphis firm. Soon after joining up, he sees things that look suspicious. Things escalate until he's involved in blatantly illegal practices with mob clients. Eventually, he ends up fighting for his life as The Firm attempts to deal with him like they do with other problem employees: by killing him.
The differences: