The Goldfish Bowl

This is not where I saw myself in five years. It's not where I said I'd be during the job interview either. Now I'm stuck in a low-level, dead-end job I have no interest in. At least I'm good at what I do - that's something, I guess. So, when I uncover suspicious activity on a new account that threatens to launder hundreds of millions through the company I work for, I report it to my superiors, going through all the official channels exactly like you are supposed to.
But what do you do when they refuse to take suspicions seriously? How far do you go when you only suspect a crime is happening? What desperate measures do you resort to in order to bring these crimes to light, especially when there's the possibility of losing everything?