The Peacekeepers (Star Trek: The Next Generation #2) by Gene DeWeese

Exploring a deserted alien spaceship, Lt. Commander Data and Lt. Geordi La Forge suddenly find themselves transported light years away – into the middle of a deadly conflict!

While Captain Picard and the crew of the USS Enterprise™ search feverishly for the missing crewmen, Data and La Forge discover they are in a station almost identical to the one they were exploring, high in orbit around an Earth-type world. Years before, the occupants of that planet accidentally stumbled onto the ship and its advanced technology – and since then have used its weapons to keep the nations on the planet below disarmed, and at peace.

Now their own arrival has precipitated a crisis on the station. Somehow Data and La Forge must find a way to restore trust between the planet below and the station's guardians up above – before a final, destructive war breaks out!