This got me thinking about the first lines in my own books. So I went back and looked them up. They vary considerably. My books are listed below, with the first line shown for each. I defined the first line as the first sentence, unless it's single word and then it includes the sentence after that. See what you think of them!
Haven duology
The Sixth Discipline: On the morning he was kidnapped, Ran-Del Jahanpur stepped out of his great-grandfather’s house and stretched to his full height.
No Safe Haven: Ran-Del watched his son press his face against the glass museum case.
Tribes: The scorpipede crawling up Hob's foot tickled, which seemed odd for something so deadly.
The Nostalgia Gambit: The thief pushed the box across the table toward me.
Shades of Empire, Alexander listened, but he heard no sound other than his own breathing.
King of Trees: Sharon York gripped the padded arms of her seat.
Saronna's Gift: A warm summer breeze caught Saronna’s veil and almost pulled it loose.
Turnabout: The first time Becca Sommers mentioned Spanish class to me it surprised me—partly because I didn’t know Becca took Spanish, but mostly because she had just that moment slid her hand under my tee shirt and raked my chest hair with her fingernails.
Tribes: The scorpipede crawling up Hob's foot tickled, which seemed odd for something so deadly.
The Nostalgia Gambit: The thief pushed the box across the table toward me.
Shades of Empire, Alexander listened, but he heard no sound other than his own breathing.
King of Trees: Sharon York gripped the padded arms of her seat.
Saronna's Gift: A warm summer breeze caught Saronna’s veil and almost pulled it loose.
Turnabout: The first time Becca Sommers mentioned Spanish class to me it surprised me—partly because I didn’t know Becca took Spanish, but mostly because she had just that moment slid her hand under my tee shirt and raked my chest hair with her fingernails.
Wakanreo Trilogy
Alien Bonds: Dina ran one hand down the smooth red fabric of her fanciest party dress.
Alien Vows, “Yulayan!” Her father’s voice coming from the com made Yulayan jump.
Alien Skies, Kamuhi Hailoaka fastened the last clasp on his sensor-enabled training coverall, pulled on his boots, and looked down at his sleeping wife.
Drifters, Jehan forced himself to breathe normally, trying to appear relaxed in front of the assembled membership of the Jeezer Killers.
Bag of Tricks, Osman’s balls!” Aveline muttered under her breath as Princess Inessa’s left heel dug painfully into Aveline’s right shoulder.
Hidden Magic, Richart let his sword fall from his grasp.
The Nameless World duology
The North Edge of Nowhere: Darius took the silver goblet from the tray and stared into its depths.
Oaths and Promises: Darius climbed the hill above the ruins and wished he had worn a heavier jacket.
Worlds Apart: Prax crouched beside the wagon wheel, trying to see through it without exposing himself to the outlaws’ line of fire.
Novella: Where Magic Rules: “Good morning, sir.”
Alien Vows, “Yulayan!” Her father’s voice coming from the com made Yulayan jump.
Alien Skies, Kamuhi Hailoaka fastened the last clasp on his sensor-enabled training coverall, pulled on his boots, and looked down at his sleeping wife.
Drifters, Jehan forced himself to breathe normally, trying to appear relaxed in front of the assembled membership of the Jeezer Killers.
Bag of Tricks, Osman’s balls!” Aveline muttered under her breath as Princess Inessa’s left heel dug painfully into Aveline’s right shoulder.
Hidden Magic, Richart let his sword fall from his grasp.
The Nameless World duology
The North Edge of Nowhere: Darius took the silver goblet from the tray and stared into its depths.
Oaths and Promises: Darius climbed the hill above the ruins and wished he had worn a heavier jacket.
Worlds Apart: Prax crouched beside the wagon wheel, trying to see through it without exposing himself to the outlaws’ line of fire.
Novella: Where Magic Rules: “Good morning, sir.”
And the winner is . .
I think for jumping the reader into the story, it's a tie between Bag of Tricks and Drifters. I would give the prize for setting the tone of the book to Turnabout. But for doing both those things at once, I think my first published book did it best: The Sixth Discipline.
Feel free to agree or disagree in the comments!