John Barnes is often compared to Robert Heinlein—fittingly for some of his books, less so for others. In his new book Finity, though, he is remarkably close to Heinlein in a number of ways. In fact, he is remarkably close to certain highly specific Heinlein novels, though he has done a very clever job of integrating them and of coming up with a new premise on which to erect his narrative.

At the start of Finity, its first person narrator is an academic living in an American expatriate community in New Zealand, engaged to another American expatriate academic. Gradually we learn that the expatriate community was established by successive generations of refugees from a Nazi-conquered America, one of the Twelve Reichs that emerged from a German victory in World War II. This seems to indicate that the reader is on the familiar territory of an alternative history novel.

As the action starts, the narrator is offered a new job at a fabulously wealthy corporation. After his interview, he falls into a series of intrigues and misadventures, during which his life is endangered. His fiancee saves him, displaying combat skills and possession of weapons that are no part of her background as we know it. At this point one of Barnes's Heinleinian sources becomes visible: Friday, and secondarily various other Heinlein novels of espionage. The unexpected lethality of the narrator's fiancee is just what we would expect.

But Barnes has further complexities in store for the reader. For it emerges that the fiancee has no idea how she learned those skill or came into possession of those weapons, and indeed had no idea that she had ever had either. In trying to figure this out, both characters and a number of their friends experience inexplicable lapses of awareness and find strange gaps in their memories and equally strange disagreements with each other's histories. All of them are exiles from America, but apparently no two of them from the same America.

To say more about how Barnes resolves this situation would give away far too much. Let it suffice to say that he does tie everything together in the end, and does so with a premise that derives plausibly from current scientific theories and from hoped-for future technologies. And both in the problem he poses, once it emerges into full view, and in the ultimate resolution of that problem, he is revisiting the ground of the other best of Heinlein's late books, Job.

In the process he offers us a number of other pleasures. His characters are a mixed lot, but even the less appealing of them carry a vivid sense of real personality. His intrigues are complex and often baffling, but they convey a sense of conviction, perhaps not least by the sheer depth of their hidden motives. His ideational content is sophisticated and starts out from an accurately presented understanding of real physics, though it makes that physics a springboard for a leap into weirdness. It was an added pleasure that he told his story in as few pages as served for most of the classic science fiction novels, with a manageable cast of characters and with no unresolved elements set up to drag the reader back for a sequel or three. I find Barnes an uneven writer, but when he wrote Finity the muse was with him.