"Heather Lawrence's long-awaited vacation to Salzburg wasn't supposed to go like this. Mere hours into the transatlantic flight, the Houston FBI agent is awakened when passengers begin exhibiting horrific symptoms of an unknown infection. As the virus quickly spreads and dozens of passengers fall ill, Heather fears she's witnessing an epidemic similar to ones her estranged husband studies for a living-but this airborne contagion may have been deliberately...