He started out thinking it was a practical joke on the part of his late uncle. However, following his posthumous instructions pulls Tom into an alien environment, and face to face with his late uncle's employer. There, he learns that he's been recommended for the vacant position. At first, it's just a job of fetching mysterious gray boxes located at various locations on earth, and tele-porting them to their intended destination by shooting a glass "gun" at them. Strange and wonderful, and a lot more lucrative than driving an Edinburgh taxi, but suddenly things get strange. He realises that things aren't as they seem. He meets others, including Fanshawe, who looks about 30, but has combat experience spanning hundreds of years, who introduces him to the network of alternate earths -- think of them as parallel universes.
Most of the "earths" are a part of a federation, and through the narrative we discover the politics, powerful inter-world organisations, underground groups, and worlds in various states of progress and/or decay. Being peopled by humans (no aliens or interstellar travel), there's also the corruption, greed, "inconvenient truths" that seem too pervasive to rectify; but also good-hearted people who simply want to see justice and mercy. Our own earth isn't a part of the Federation, and is in trouble.
Alistair Potter plunges us into this world with a style that, though one couldn't exactly call it witty, it invites the reader to not take things too seriously. He pulls us straight into the story, and doesn't let us stop unless we really have to fix dinner, or get some sleep. It's great storytelling. One does notice one or two things, one being that everyone seems to speak English but there's no mention of a "babble fish" or whatever technology they use on Star Trek to understand aliens on first contact. But the story is so good, it's easy to ignore that factor.
Over all, it's a great story, definitely worth a read.
I got my copy free in exchange for a fair honest review, which wasn't difficult to give because it deserves five stars anyway.