Another bit of Glen Cookery. Outside of The Black Company this is probably his most famous and well regarded book; it takes the general formula of _Das Boot_ and submarine warfare and flings it all into space. I liked the result, and it benefits from the standard Cook Qualities of grounded characters drawn from his personal military experience, surprisingly intelligent and inventive world building, and well plotted and fast moving events. The basic sci-fi conceit is that human scientists have discovered a way to make small ships nearly disappear into their own pocket-universes, connected to the real universe by only the most microscopic of apertures. While pocketed, the ships are nearly invisible and untouchable (depending on how far up their own asses they have gone), and are only constrained by their fuel stores, the heat that they build up, and the gradually increasing weirdness of physics the further they narrow their aperture. It's the sci-fi equivalent of a submarine diving as it renders them difficult to detect and harm so long as they are submerged. The narrator of the story volunteers to join the crew of one of these ships as it sets out on a months long raiding mission. There's a steadily ratcheting tension as the ship and its crew face increasing danger from enemy action, the depletion of their ship and supplies, and a steadily worsening strategic situation. It is a neat plot that's done well, and it steadily introduces the detailed and crunchy concepts of its sci-fi world in a well thought out and considered way.