An archeological expedition to the Yucatan has discovered a Mayan city deep in the jungle. The city of Xitaclan has been undisturbed for centuries. While exploring the team lead by Cassandra Rubicon disappears. The father of Cassandra convinces the FBI to investigate and naturally the FBI chooses Mulder and Scully. Mulder being the more imaginative one thinks that there is an extraterrestrial connection with ancient astronauts. Scully tends to believe in a more mundane explanation.
When they arrive in the lost city they run into a whole boatload of conflict. A shady guide who deals on the side in stolen artifacts. Superstitious natives that still believe in blood sacrifice. A police chief secretly in charge of a Yucatan secessionist terrorist movement. Sightings of mythical feathered serpents in the jungle. A strange alien spacecraft inside the pyramid. After finding the team murdered and dumped in a sacrificial pool all hell breaks loose when a covert U.S. military commando group shows up to blow up the city to stop a mysterious radio signal emanating from the pyramid. It ends in a battle between the commandos and the secessionist with a visit by the mysterious aliens.
The second book by Anderson is even better than the first. I think this is my favorite X-files book. The exotic location of the Yucatan was an excellent setting. Throw in aliens and government conspiracy and you have a classic X-files story. The history and culture of the Yucatan was well researched and informative. Lots of fast paced action and an interesting story that keeps the mystery going makes this a worthy book in the X-files series.