I also recommend the entire Stephanie Plum Mystery series by Janet Evanovich. The first book is the toughest, though all of them are pretty light. Most of them a pure comedy.
One for the Money
Two for the Dough
Three to get Deadly
Four to Score
High Five
Hot Six
Seven Up
Hard Eight
To the Nines
Ten Big Ones
... and there are about for 4 more