Marque and Reprisal follows up the first book pretty directly. Ky may have thought that having dealt with mutineers and pirates, everything would be back to normal, but she barely has time to land her cargo before a shadowy interstellar conspiracy attacks her family. Most of the family's leadership, including Ky's father/the CEO are killed in the attack, and in the wake Ky is cut off, her cargoes uninsurable, lines of credit frozen, and herself and her ship under attack by assassins and saboteurs. Ky's mission is to survive, figure out who the enemy is, and strike back.

To help out with this, Moon introduces disgraced cousin Stella Vatta, who has redeemed herself as a courier and spy, and insterstellar man of mystery Rafe, a spy working for the Interstellar Communication monopoly. It seems that a conspiracy is eating at the heart of ISC around mobile ansibles which might break their monopoly on FTL communication. And the Vattas are either targets of opportunity, or part of a plan of revenge orchestrated by a truly vile blacksheep of the family.

Ky winds up in an the equivalent of an interstellar knife fight, using deception and EMP mines to take out her enemies (oh, and killing several of they in hand-to-hand space suit combat). And with a new ship, and a mysterious letter of Marque from a patron in the Slotter's Key military.

I'm torn, because so much of this series is solid, but so much important stuff is just... hanging there. The grand interstellar conspiracy and mechanics of FTL communication are so vague that it seems like literally anything could happen. For every problem Ky solves through her own resourcefulness, there are three where the solution is handed to her on a platter. And for a setting which is trying to evoke some kind of Age of Sail-esque mercantile adventurism, so much of it just plods.