If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
The Underground needs a new leader! Drive through 12 levels, and compete with some very tough guys, with better tuned cars then yours. As you work your way up in the levels, the amount of money that can be won, will rise too. You will have to complete five laps in the first race in record time and finish on first place, only this way can you win the reward, and upgrade to the next, more harder level.