I was thinking about some of my favorite children's books & how their first line drew you in the story. Sometimes action, sometimes setting. Here are a few:

" Where's Papa going with that ax?" said Fern to her mother as they were setting the table for breakfast.
CHARLOTTE'S WEB E.B. White

Today, Monday, Wanda Petronski was not in her seat. But nobody, not even Peggy and Madeline, the girls who had started all the fun, noticed her absence.
THE HUNDRED DRESSES Eleanor Estes

A wild, ringing neigh shrilled up from the hold of the Spanish galleon. It was not the cry of an animal in hunger. It was a terrifying bugle. An alarm call.
MISTY OF CHINCOTEAGUE Marguerite Henry

I come from a family with a lot of dead people.
EACH LITTLE BIRD THAT SINGS Deborah Wiles

The first place that I can well remember was a large pleasant meadow with a pond of clear water in it.
BLACK BEAUTY Anna Sewell

Buck did not read the newspapers, or he would have known that trouble was brewing, not alone for himself, but for every tidewater dog, strong of muscle and with warm, long hair, from Puget Sound to San Diego.
THE CALL OF THE WILD Jack London

I remember the day the Aleut ship came to our island.
ISLAND OF THE BLUE DOLPHINS Scott O'Dell

A column of smoke rose thin and straight from the cabin chimney. The smoke was blue where it left the red of the clay.
THE YEARLING Marjorie Kinnan Rawlings

Squire Trelawney,Doctor Livesey, and the rest of these gentlemen having asked me to write down the whole particulars about Treasure Island, from the beginning to the end, keeping nothing back but the bearings of the island, and that only because there is still treasure not yet lifted, I take up my pen in the year of grace 17__ and go back to the time when my father kept the Admiral Benbow Inn, and the brown seaman, with the saber cut, first took up his lodging under our roof.
TREAURE ISLAND Robert Louis Stevenson