Agent Luvvin D. Loglines likes her queries with a one-sentence pitch/summary up front.
1. Are Publishers Marketplace deal announcements a good model? To use an example I pulled out of my hat: In SHIPWRECK, INTERRUPTED, a 19th century Japanese mermaid must choose between her gang's mission to destroy foreign ships and super-hottie Admiral Perry, in a ludicrous deal, etc. etc.
2. What if your hook is in the title? If you're querying IT, it behooves you to mention killer clowns will make an appearance. But if you're querying the novelization of KILLER KLOWNS FROM OUTER SPACE, how do you pitch it without re-mentioning the clowns' motives and place of origin? (Title-Hook Syndrome pops up frequently with children's books-- e.g., FROG AND TOAD ARE FRIENDS.)
Pub Mkt listings can be good examples. I save ones that I think are good so I can look at them when I'm writing my own deal announcements. Not all of them are though. And how you'll know the difference I do not know.
Which brings us to why I despise asking writers for log lines in a query: log lines, good ones, are BRUTALLY hard to write well. I practice (as do all the agents here) in a group meeting with our film guys, and I learn something new every single week. And I've been doing this a LONG time.
Here's my starting point for Crude Oil, Crude Money:
A swashbuckling, smooth talking billionaire signs the deal of a lifetime to control all of the Saudis' oil shipments. Multiple sinister and divergent interests ally themselves and plot to reclaim the golden goose.
Here's what got posted to PM
Former Washington Post Mid East bureau chief Tom Lippman's CRUDE OIL, CRUDE MONEY, examining Aristotle Onassis' bold gamble to corner the crude oil shipping market by signing a deal with the King of Saudi Arabia, to the dismay of British and US oil companies, the Dulles brothers in DC, the newly elected prime minister of Egypt Gamal Nasser, and the encroaching Soviets eager to build power in the region to Hilary Claggett at Praeger, in a nice deal, for publication in 2019, by Janet Reid at New Leaf Literary & Media (World English).
Here's the logline for a short story by Phillip DePoy
In "Accessory", Foggy in his role as Child Protective Services officer is called in when a young girl is a witness to a murder that makes no sense to anyone hearing about it. Now he's got to figure out whodunit and more important whydunit, before things get a lot worse in Fry's Bay Florida.
And here's the logline for a short story by John Haggerty
In "Shelter" Chekhov's gun is a bomb shelter.
None of these follow the same rules or format.
I think they all do the one thing a log line has to do: entice someone to read on.
There is no template, there's no one right answer.
Generally however log lines should show the decision a character has to make, be liberal in use of adjectives (rather than verbs--which makes me nuts as you might imagine) and convey the tone of the book.
And a partridge in a pear tree would be nice too.
Like I said, loglines are brutal. Since most of you have trouble just getting plot on the page, if someone asks for a logline I'd ignore it for a more complete rundown of what's at stake in a novel.