There was a relentless forward motion to the man. The universe might knock him down over and over again, but unless he was dead, he’d just keep getting up and shuffling ahead toward his goal. Holden thought he had probably been a very good scientist. Thrilled by small victories, undeterred by setbacks. Plodding along until he got to where he needed to be.

The story of the first book, of an alien protomolecule seemingly indestructible, intelligent and lethal to humans, expands to another level, where politicians and planets get involved. The plot is driven ahead by not two, but four protagonists: the captain – James Holden, the doctor – Prax, the politician – Avasarala and the soldier – Bobbie. While each starts from its own background, the protomolecule brings them all together, trying to stop the increasing menace. While planetary governments try to weaponize this alien artefact, the molecule learns and becomes increasingly intelligent. Our four heroes maneuver around politics and dangerous situations to destroy the threat, but the war goes on.

The book introduces two memorable characters: the UN politician from Earth, Avasarala and the Martian female soldier, Bobbie. They team together, more by chance than design, to keep the two planets fighting against the common threat. Avasarala is diminutive, elegant, sophisticated, foul speaking, machiavellian, happily married and old. Bobbie is the opposite.

I rarely continue books in a series, but this space saga is exceptional. Great story building, memorable characters with credible motivations, a tight plot, hard science fiction, great writing – overall, an truly enjoyable reading.

The book’s title is unusual, as Caliban is never mentioned in the book. It is, in fact, a reference to the character Caliban in Shakespeare’s “The Tempest.” This character tries to free himself from subjugation of his masters, as the protomolecule tries to shake the bondage of those who try to weaponize it.

Excellent series, that goes to about 9 books. Long, but worthy reads.