After having identified what threatens the lifeforms of the Interspecies Union biologist Dr. Mackenzie Connor returns to her life as a salmon researcher. The return proves difficult, though. Meeting the alien has not only provided a larger frame of reference but has also resulted in vivid flashback nightmares and a feeling of inadequacy – she is worried that the people responsible for handling the threat are looking in the wrong direction, she also worries about her vanished colleague, Dr. Emily Mamani, but she is forbidden by the Ministry of Extra-Solar Affairs to reveal anything to anyone about the true reasons for her absence from work.
Unbeknownst to her others wants access to her and her insights and she ends up being part of a multi-species effort to find a way to tackle the combined Dhryn/Ro threat to life. This proves a challenge, as the team assigned to her is suspicious of her motives.
The characters are both fun and profound, most of them with his, her, its or their own motivations and quirks and the story itself a well paced and balanced mix between action and reflection.
While part 1 (Survival) can stand on it’s own Migration is very much dependent on it’s successor (Regeneration) to provide an ending. This is, however, not a problem, because the tale holds the reader in constant suspense, making it imperative ;-) to have the concluding part near at hand when finishing Migration.
I highly recommend the Species Imperative trilogy. Start with the first book, though, if you want to get things right.