Query letters are tough. Every agent wants something different. Getting a handle on what each one is looking for is difficult, but there are two things that are consistent: a new voice, and the hook.
On the front of the book, "Hooked," written by Les Edgerton, it says:
"Write fiction that grabs readers at page one and never lets them go."
SO TRUE! If you don't hook your readers from the get go and take them on a wild ride, they may never pick up another book you have written.