The Cat's Table is the lowest table on the social order of an ocean liner - basically the kiddie's table of the most un-important. At this table, the main character of the story, Michael (or Mynah) finds companions on a 21 day long cruise from Ceylon to England. He is alone (except for a neglecting relative of sorts) and he and his companions engage in general children's shenanigans.
The book almost reads as a series of short stories or character sketches through the book, but a mystery shows up part-way through the story, something dangerous and interesting for the boys to try to piece together.
Most of the story is told through Michael's 11 year old eyes, but there are flashes to the future where grown-Michael thinks back upon his journey and understands the influence this journey has had upon his life (and the lives of others).
It's an easy read, with phenomenal prose. Without using any shock-factors or plot devices, Ondaatje weaves an incredibly engaging and compelling story with beautifully fleshed out characters and amazing verisimilitude.