Here's a sample query letter to give you an idea of what agents are looking for. See the page on query letters for an explanation of the rationale behind writing the query letter this way.
Here's the letter:
Dear Ms Agent,
I’m contacting you as I see you represent Mr Author, and my women-in-jeopardy novel, Fortune’s Favourites, has echoes of his work in its exploration of the inevitable secrets families try to hide, and the price they pay for that.
High-flying Dublin barrister Chloe Byrnes has to clear out her recently-dead grandmother’s attic, and comes upon her diary. She discovers her grandmother’s role in the Irish Easter Rising and the burden she has carried ever since; a burden which is still impacting Chloe and - she realises - several others. Can Chloe make amends after all these years? Who is trying to stop her doing that, and how far will they go?
I am a professional journalist working with the Daily Broadsheet. I completed the Dublin Writers’ Museum creative writing course and had a short story published in their anthology Disparate Writers which reached No. 4 in the Irish Bestseller lists. I have also had three short stories published in various women’s magazines. Fortune’s Favourites is my first novel.
I would be more than happy to send you some, or all, of my manuscript upon your request.
You'll note how brief this sample query letter is. Brief is good as literary agents are busy people. But note too how I included all the salient information :
Paragraph 1 explained clearly that submitting to this agent was not an arbitrary choice.
Paragraph 2 gave a short-but-intriguing (I hope!) synopsis of the plot. (Actually, it has intriged me. I think I might write that novel, I need to find out what happened!)
Paragraph 3 gave the author biography, including only relevant information.