Star Trek The Next Generation - A Time to Hate

the long version

The recurring blood feuds between the Bader and the Dorset ended mysteriously a century ago when both races colonized the planet Delta Sigma IV. But, unknown until now, it was a reaction to a naturally occurring gas that led to their harmonious existence... a reaction that would eventually mean certain death for the planet's inhabitants. What the Enterprise crew believed was a cure for the population -- a treatment introduced into Delta Sigma IV's environment by Kyle Riker, a man at odds with his son, Commander William Riker -- has instead triggered worldwide carnage, as long-suppressed aggression and hostility are suddenly and violently unleashed. Caught in a world on the brink of self-destruction, Captain Picard -- a man still waging his own personal battle for redemption in the eyes of his commanding officers -- must somehow find a way to resolve this catastrophic event and save his crew, even as the implications of his actions may ultimately doom an entire race....