The second Expanse novel was pretty good, but felt like a bit of a let down after the first. Essentially it reboots the basic premise of the first novel with some small tweaks, and lets that be the story line for Holden and his crew.

What redeems the novel is the secondary (one might say primary) plot revolving around Chrisjen the politician. Reading Caliban's War, it becomes understandable why in the TV series they kind of collapsed both novels into one season (they didn't), because it cuts out a fair bit of duplicate plot.

This is not to say that the second instalment is bad - far from it. But it could have some more to differentiate it from the first.

If the rumours are true, and the series is inspired by the events of an RPG campaign, then this actually makes some kind of sense.

For one thing, throughout books #1 and #2, the protagonists get in worse and worse shape. At the end, then, there's a "reward event" which sees them patched up, and their fortunes improved.

But more importantly, it feels like the protomolecule reveal from book #1 wasn't entirely thought through. You were left with some kind of half-averted threat that never really made sense entirely. The ending of book #2 suddenly turns this threat into a new event that opens up possibilities for further exploration, just as if the authors finally had a plan in place for what was supposed to happen - never mind that a bunch of this plan half contradicts much of the speculation in book #1.