Some people call this the “log line” or some other such thing, but it’s basically one sentence which tells what you book is about. I think I called the “one sentence blurb” somewhere else.
For example, the story of The Hobbit might read:
A hobbit is persuaded by a wizard to accompany eleven dwarves in order to break into their former home, which is currently occupied by a dragon.
Or something like that.
So what’s my upcoming wild ride? Here’s what I’ve come up with so far:
A cattle rancher returns home to find his lover dying and must renegotiate his relationship with his soulmate: her husband.
I’m writing a more mundane novel for NaNoWriMo (book #2 in my series), but once I’m done with that this one is next on the queue.