Dirgo was the captain of the mining shuttle Nenebek in the 2360s. In 2367, he was sent to transport Captain Jean-Luc Picard to Pentarus V to arbitrate a miners' dispute. Wesley Crusher accompanied them on the mission.
His ship, which was in poor condition, crashed on Lambda Paz, a moon of Pentarus III. The moon was a desert, and his ship had no emergency food or water. They found shelter in a cave that contained a fountain of water, but were prevented from getting to it by a force field. Dirgo tried to shoot through it, but an energy sentry knocked him down and caused a rockslide, injuring Picard. Dirgo tried to use a phaser again, and he was enveloped in electrically-deposited selenium fibers by the energy sentry. (TNG: "Final Mission")