Anton and Cecil are young brother cats, living in a seaside town. They are very fond of each other, and very different-- Cecil feels the pull of the sea, and spends his days aboard fishing boats, while Anton loves to listen to sea shanties, and spends his nights in the taverns. But it is Anton who first truly goes to sea, impressed into ratting service on board an ocean-going barque....poor Anton, who never even liked mousing on dry land.
But Cecil is determined to find his brother, and boards a ship for an ocean-going adventure of his own. They travel through a series of adventures, good and bad, meeting friends and enemies, mercenary pirates and kindly petters-of-cats, never quite giving up hope. Because there is an ancient piece of cat lore that seems to promise that one day they will be reunited....
So it's a perfectly fine, cat-full story with a nice emphasis on sibling loyalty, and adventures that are exciting (encounters with other animals, a storm at sea, pirates, etc.). Anton and Cecil are appealing (perhaps even enough so to win over dog-lovers). There's a lot of luck involved, but not so much as to overpower the agency of the cat protagonists, I'd be happy giving it to a strong reader as young as seven, and an older reader up to 10 or so.
However, the older reader might start questioning the mystical element of the cat lore that inspires Anton and Cecil. I myself never quite figured out if it was a natural phenomena or a fantastical element. And there was one bit that bothered me lots-- I think it is not fair to the reader to get rid of all the living people on board a ship by simply saying: they disappeared overnight, while the cat (Anton, in this case) was asleep. What????? So if you do give this to a reader with an inquiring mind, you might want to have some sort of answer ready! Update: Lisa wrote me to say that this episode was inspired by the Mary Celeste, so there you go.
Disclaimer: review copy received from the publisher for Cybils consideration.