Branded by Fire (The Psy-Changeling Series)

When a brilliant young researcher is kidnapped, DarkRiver sentinel Mercy, a cat, and SnowDancer lieutenant Riley, a wolf, must work together to track the young man - before his shadowy captors decide he's no longer useful. Along the way, the two dominants may find that submitting to one another uncovers not just a deadly conspiracy, but a passion so raw that it'll leave them both branded by fire.