The crew of Deep Space Nine are on the USS "Defiant", returning to Bajor with the sacred Bajoran Orb of Time, which is being returned by the Cardassian government after being stolen during the occupation. They pick up a hitchhiker, a human called Barry Waddle. Suddenly the ship finds itself more than one hundred years in the past and approximately 200 light years away from its previous location, near Deep Space Station K7 and the USS "Enterprise". They discover that the hitchhiker was Arne Darvin, a Klingon agent disguised as a human who was caught by Captain Kirk on "K7" after poisoning a shipment of grain.