The story begins with some mysterious glowing objects falling from the sky, and intrepid humans taking a closer look at said objects. As they approach the object like rock pinch them, some dying and others becoming highly aggressive and very strong.
After a couple of dozen of them are infected they get abducted by a spaceship, formed into groups and forced to fight with batons battle royale style. The winners are taken to a space carrier, and assigned to a small ship crewed by 4 to 6 humans. They discover that the carrier has multiple alien races, each crew representing their planets, and they have insignia that change with rank, first rank is a circle, I cant remember the second one, the third rank is a triangle, the forth is a diamond shape with four sides, the more sides the higher the rank.
At the end of the book after the battle, every crew is return to their planet, the Captain of the human crew tricks the alien alliance and decides to crash his ship on Earth to give a change to humanity to studied it, and the aliens not recovering it because for them is old tech, and not worth the time and effort to recover it.