A commercial plane carrying almost two hundred people crashes into the Atlantic Ocean. Eyewitnesses on a yacht say the flight, bound for the United States from Portugal, was on fire as it fell from the sky. The search is on to find the wreckage.

Seventy two hours later, another plane goes missing, American Airlines 44, bound for New York from Paris, France; with terrorism now suspected, the NYPD’s Counter-Terrorism Bureau are asked for their assistance. The scale of the case and the distances involved are factors Sergeant Matt Shepherd’s team have never encountered before.

And it soon becomes clear the five detectives will have to be deployed thousands of miles apart if they’re going to stand a chance of finding out who’s responsible for the attacks.

Alice Vargas and Lisa Marquez, sent to find an air marshal whose record suggests he’s up to more than just flying mission flights. Harry Ledger, dispatched to the American Airlines wreckage site in the Atlantic to see if there are any clues as to how it was brought down.

And Sam Archer. Despite an unexpected complication that could affect his capability, Archer is sent somewhere he has never had to investigate a crime before.

35,000 feet up in the sky.

As the usually close-knit team find themselves spread out around the world, from Mexico to London, Las Vegas to Paris, the investigation pushes them all to their limit as they face an enemy more intelligent, determined and merciless than any they have faced before.

Hundreds of lives have been lost and thousands more are on the line.

One mistake and gravity will do the rest.