The Navigator (by Eoin McNamee)

Soon he finds out that evil beings called the Harsh have reversed time, that the Workhouse is an island in time, and that the people there, called Resisters, sleep through the centuries and awaken when needed to fight the Harsh. Owen himself has a part to play in defeating the Harsh and setting time back on its normal course. But he's not sure whom he can trust, and some of the Resisters don't trust him -- they believe that his father was a traitor, and Owen may be too.

Adult author Eoin McNamee pens an intermittently exciting variation on an archetypal fantasy theme for his first children's book. The details are imaginative, but unclear. Who the Harsh are, where the Resisters came from, how it all works -- none of this is really explained. This might be less noticeable if the characters were more compelling, but they're mostly flat and interchangeable.

The ending is even more mystifying than the rest of the story. The action is fun at times, though it sometimes drags, and there are hints that there might be more backstory than the author is letting on. This is intended to be the first of a series, but it doesn't leave the reader panting for more. It might appeal to fantasy fanatics who have run out of more compelling fare.