This first part of a duology is a pretty exciting read that has ties to both Vanguard and TOS.
The Defiant which mysteriously vanished in an interspatial rift back in "The Tholian Web", after having investigated the death of every inhabitant on a Klingon civilian colony in the Taurus Reach and beaming a strange, seemingly Tholian device on board ("Vanguard: What Judgments Come"), reappears in normal space, trapped between the dimensions. The da Vinci gets sent to recover the ship under Tholian supervision. But the Tholians aren't going to allow the century old artifact on the Defiant to be further investigated and try to destroy both, the Defiant and the da Vinci.
After concentrating on Soloman for the first 3 books, this is the first one that takes a look on the ensemble in general. And the characters work - even if it's not really plausible that the captain of the da Vinci leaves the ship to accompany Gomez on the away mission to the Defiant. He doesn't have any engineering knowledge and could have explored the Defiant out of historical curiosity once they got her free of the rift. But it, of course, serves to put Commander Duffy, the second officer and untested so far in the big seat in command and therefore puts the focus on him.
The Tholians have remained mysterious in TOS and the later TV-installments, so it's fabulous to see them - and the issue of the lost Defiant - return here... something that gets even more background with prior knowledge of the events in Vanguard (which were published 10 years after this e-book was released in 2001 - shows what planning went into that series!).
What I don't get, though, is the ending of this story: The Tholians attack both Defiant and da Vinci, da Vinci retaliates and the Tholians withdraw. And why exactly should they who attacked without provocation view the da Vinci's counterattack as "an act of aggression"? Should the da Vinci just surrender and let themselves be destroyed? That didn't make much sense. But perhaps there'll be an explanation in the conclusion.
Overall - good read, so far (except for that huge question mark) easily the best part of the S. C. E. I hope part 2 will live up to this!