Star Trek: The Next Generation: Requiem

Twenty-five years ago, Captain Jean-Luc Picard conducted breakthrough negotiations with an aggressive race called the Gorn. Now, on the anniversary of that achievement, Captain Picard and the U.S.S. Enterprise™ are headed for the Gorn Homeworld to continue that important work.
But when the ship stops to investigate a mysterious alien artifact, Captain Picard is suddenly hurled through time and space. Just as Commander Riker and the Starship Enterprise™ crew begin an impossible search for their captain, the Gorn summit goes terribly wrong.

As war looms over the galaxy and Picard is desperately needed on the Gorn Homeworld, the captain finds himself stranded in the past on a planet called Cestus III at a crucial turning point in Federation history. Now, caught in a deadly situation that challenges Picard's most cherished beliefs, he must weigh the fate of a world against the future of the entire Federation...