Odo's mentor visits the station, and a creature escapes.
Dr. Mora Pol, the Bajoran scientist who studied Odo after he was found, tells him of DNA readings like his own on a Gamma Quadrant planet. Odo goes with him and Dax and they bring back a tiny life form, though Odo is embarrassed by Mora's fatherly attitude. The planet's volcanic gas knocks out the others.
Back on the station the sample appears to escape, and a creature attacks Bashir. Mora realises that the creature is Odo himself, changed by the gas during the times he returns to liquid form. Mora admits his own pressure on Odo triggered the changes, helps lure the creature into a force field where it reverts to Odo, and the two reconcile once the effect is cured.