Everyone has their own ideas on what constitutes a good query letter. My beginning and middle consist of what I hope is, an excerpt grabber from my book. My letter ends with the usual, 'if you would be interested in seeing the manuscript, I would love to send it to you,' etc.
I had what I thought was a good query letter and a great premise for The Crystal. I thought seeing a mysterious stranger in a crystal ball was a 'novel' idea.
After drowning my sorrows and stretching out my waistline, I sat down and took a long hard look at my letter. I decided to add one sentence. That one sentence turned my dings to requests. I even had an agent ask if she could use my letter as an example of how to write a great query letter in a workshop she was giving.
The sentence I added consisted of five little words....'Ecstasy coursed through her body.' Go figure.