CALCULATED IN DEATH by J.D. Robb (aka Nora Roberts) is part of her In Death series featuring Eve Dallas. I don't know how she does it, but this series continues to get better and better!
When Russet McGinnis and Maxen Pryce take on the responsibility for a late-season archeological dig, their quest for more artifacts is cut short when an early nor'easter forces them to close down the project until the next spring. The flight home takes a sudden ominous turn as they encounter a strange swirling cloud bank that surrounds them despite Max's attempts to avoid it. Lost in the wilderness after their plane crashes, Max and Russet must depend on each other's love and courage to survive.
Their struggle for survival compels them to bare their hidden secrets and acknowledge their feelings for each other. Homesickness and potent irresistible desire draw them closer as they work together to survive abduction, inexplicable attacks on their plane, encounters with shape-shifters, and a wild ride in a goddess-driven tornado until at last they confront their true destiny.