Alien Expedition — Pamela F. Service

In the third book in the series, young Alien Agent Zack Gaither is sent to Mongolia to liaise with his fellow agent Vraj, whom we met in Camp Alien. Vraj's people, the Tirgizians, are exploring the area for evidence of dinosaurs, whom the Tirgizians believe to be their long-lost ancestors. Enter the Kaipa Kapa Syndicate, a mixture of bad guys, including the Gnairts who'd previously tried to kill Zack and Vraj. The syndicate kidnaps the Tirgizians, and with the help of two local Mongolian kids, Zack and Vraj manage to free them and avoid being discovered.