Star Trek: Grand Designs (Star Trek: Starfleet Corps of Engineers Book 39)

Tensions between two planets in the Rhaax system have abated to the point where the sides have agreed to disarmament. The S.C.E. crew on the U.S.S. da Vinci is sent along with a Federation diplomat to act as weapons inspectors to make sure that the terms of the cease-fire and disarmament are followed.
But soon the S.C.E. learns that neither side has any intention of truly disarming -- and then Tev, P8 Blue, and Soloman are captured by one side. Captain Gold must find a way to rescue his crew, and keep the peace, before both planets explode!