A solid, propulsive work, Steal Across The Sky by Nancy Kress (reserve it here) focuses on the events following the first contact between our planet and scientifically advanced extraterrestrials calling themselves the Atoners, set some ten or so years in the near future.
Ten thousand years previously, the Atoners populated seven pairs of binary planets with humans abducted from our world. The Atoners recruit human volunteers called "Witnesses" to observe each pair of planets, with a third member of the respective crew monitoring the Witnesses on their assigned planets. The first half of the book details the exploits of two of the Witnesses, Cam and Lucca, along with their observer Soledad, on their individual assignments. Predictably, both are unable to prevent getting involved with the events on their planet, resulting in tragedy for one of the planets' inhabitants in particular.
Then all twenty-one crew members, armed with knowledge of a (seemingly) shocking discovery that might have great sociological and potentially disruptive impact on our world, return home in the second half of the novel. To say more would give away too much of the plot, but author Kress manages to cover various social, political and religious fields of interest, while also crafting an exciting science fiction thriller, as she shows the ramifications of the impact the Witness' return brings on Earth.
Ms. Kress leaves herself wiggle room for sequels (and possible prequels) by the novel's climax, thanks in part to some dangling plot ends left unresolved. (Frankly, the mutual plight of of the insufferable Cam and her fellow Witness, the holy roller ex-cop Frank, ends way too abruptly for me, which is why I'm going with the sequel possibility.) Her characterzation is believable, with appropriate shades of gray in her protagonists. The readers will find themselves fully involved with the characters regardless of their level of likability (or lack thereof).
Look also for various "in-joke" references to the works of Arthur C. Clarke and (my favorite) the classic 70s TV series Space: 1999, among others, sprinkled throughout the book. I'm always a sucker for those kind of things.