Nightshade Star Trek: The Next Generation Book 24

After two hundred years of civil war the planet Oriana is dying. Most of the surface vegetation is gone, the air is nearlyy unbreathable, and the people themselves are dying. Now, the two warring factions have finally sat down to talk peace, and Captian Picard and the U.S.S. Enterprise™ are sent ot help them negotiate a settlement.
Picard, Lt. Worf, and Counsellor Troi beam down to Oriana, just as the Starship Enterprise is called away on another urgent mission. Alone on the planet, the U.S.S. Enterprise team learns that htere are people that would rather finish the devastating conflict than talk peace. Suddenly, Picard is accused of murder nad the delicate negotiations have fallen into the hands of Lt. Worf.
Now, Worf and Troi must unravel the truth and prevent planet-wide disaster, before time runs out for the people of Oriana and the crew of the Starship Enterprise.