Becoming an undercover police officer or agent is one of the riskiest career paths a law enforcement official can take. Joining an intelligence agency is a major risk in and of itself, but going undercover as a cop raises the danger level up a few notches. And the home front isn't much healthier. From frustrated partners to demanding bosses, the stress of the job makes it one of the most physically and emotionally demanding ones out there. Despite rigorous training and high-tech gadgets, going undercover entails a life on the edge, living a lie that can be busted at just about any moment and, at times, lead down a path to becoming a dirty cop.