 Lt. Jadzia Dax ( Terry Farrell ) returns from the Gamma Quadrant in her runabout with a woman that Chief Miles O 'Brien ( Colm Meaney ) recognizes as Vash ( Jennifer Hetrick ) from his time on board the Enterprise . Although the crew is unaware of his presence , Q ( John de Lancie ) — a nearly omnipotent prankster — has also stowed away on the runabout . Vash explains that she has spent the past two years in the Gamma Quadrant , but she describes her method of getting there as a " private matter " . During their trip back to Deep Space Nine , the vessel undergoes a series of unusual power drains . 
