A Whisper from Shadow (Shadow Gods Saga, Band 3)

In old Mexico the gods were real, or so it was believed ... and they left a terrible heritage. Working on a remote dig, archaeologist Lauren Hopkins discovers an extraterrestrial craft buried in an ancient Mayan pyramid. Instead of being a boon to mankind, the discovery triggers a global confrontation. The country that can seize and control the alien technology can control the world.
The Serrll Combine, embarrassed that one of their old scoutships got mislaid, knows that it must act quickly to avert open warfare on Earth. The newly promoted First Scout Terrllss-rr, and on his first mission as a Diplomatic Branch agent, is sent to destroy the craft and avert a global catastrophe. It should have been a simple mission, but Terr did not count on Lauren being in the ship when he planted the demolition charges. About to make his escape, Terr and Lauren are shot by patrolling guards. Lauren recovers, but Terr faces disciplinary action for bringing the humans to the Serrll Moon Base. For Lauren, the aliens turn out to be much more than the Mayan gods of old.