After the devastating Borg invasion which ended in the Destiny-trilogy, the main galactic powers formed two blocks: the Federation and its allies on the one side, and the Typhon Pact, consisting of the Romulan Star Empire, the Breen, the Tholians, the Tzenkethi, the Kinshaya, and the Gorn, on the other.
This novel starts with the Breen stealing plans for the slipstream engine which offers the Starfleet ships a unique advantage over everyone else. Bashir is assigned to infiltrate the Breen world of Salavat to get ahold of the plans, destroy every trail of the plans within the Breen system and any prototype the Breen might be constructing there. His partner in this operation is Sarina Douglas, his one-time lover and fellow augment.
The operation itself wasn't really too exciting because the outcome was obvious from the beginning. I enjoyed the insights into Breen society - a people consisting of a multitude of species, all hidden by a uniform mask and suits, any trace of individuality practically nonexistant, even forbidden and gravely sanctioned. On the other hand, those suits help Bashir and Sarina to gain access - even though the plausibility of equipping a simple suit, even if not form fitting, with the multitude of tools mentionned in the story, is stretched very thin, indeed.
And of course, we have the characterization of Bashir who feels quite lonely on DS9, without a purpose, and rediscovers his feelings for Sarina during the mission. But Sarina's agenda might not be as benevolent because during the final pages it becomes clear that she was ordered to seduce Bashir in order to get him to join Section 31... so are any of her feelings true? And even Bashir's remorse over having to kill during the mission (which IMO could have been avoided because in that instance a heavy stun beam would have sufficed in order to get access to the operations center) had been accounted for and worked towards to secure that goal by Section 31...So where's Bashir going next? Is he going to fall right into the trap? This might have worked better for me if I was actually eager to read more of Section 31. But TBH, I was quite fed up by them at the end of the TV-series, and while I enjoyed Abyss, I'm not actually looking forward to seeing Bashir once more fighting them.
Last but not least, we get a further glimpse into Ezri's command of the Aventine and her crew... unfortunately again, with wise-cracks and miracle-workers - but apparently, that's just how things on Starfleet ships work (at least according to Mack).
Overall, a decent spy mission, a glimpse into a foreign society, a rekindled lovestory which might not be everything it's made out to be... and the ever-looming threat of Section 31. What's next?