One thing is for certain with this game, and that is that you cannot claim that the name is misleading. The action takes part in a Diner, and you will be dashing about all over the place. Oh, and it's the second game, so everything fits perfectly into place.
Diner Dash 2 puts you in the role of Flo, the heroine from the original game. Having already set up her own successful chain of restaurants, she's now decided to help her friends do the same (because they're presumably incapable of succeeding on their own). Naturally the action begins in small diners, and you'll gradually work your way up to bigger ones as you progress.