Abaddon’s Gate is the third in the Expanse series of books, following Caliban’s War.  It is set in a solar system with three factions: Earth, Mars, and the less organized “Belters” living in the asteroid belt and the moons of Jupiter. In the previous book, an alien substance termed Protomolecule constructed a device in the clouds of Venus then launched itself out past Neptune to form a giant ring structure.

The story starts with a fully formed Ring outside the orbit of Uranus.  Mars, Earth, and Belters have all sent probes into the ring, only to have them disappear.  A rogue Belter tries to run through the ring at high speed only to turn into Belter juice as the ship violently decelerates.  Everything is at a standstill until a hacker causes our heroes ship, the Rociante, to broadcast a message saying the captain was declaring the Ring property of Belters and threatening to shoot anyone who came near it.  This marks the Rociante for death.  In the process of avoiding missiles our intrepid crew manages to enter the ring by reversing thrust at the last minute and entering slow enough.

Realizing the Ring can be entered, all sides send in ships.  After that the story covers distrust between the three fractions, between those who think the Ring should be destroyed and those who do not, and the Ring itself which is programmed to repel “threats”.

Abbadon’s Gate is a strong third book in the series.