In 2267 the USS Enterprise assisted Deep Space Station K-7 in its attempts to colonize Shermans Planet. Captain Kirk was able to uncover a Klingon plot to undermine the stations efforts by poisoning a shipment of quadrotriticale bound for the planet. Kirk revealed that Arne Darvin, assistant head of the development project, was in fact a Klingon national operating as an undercover agent. The Klingon government abandoned Darvin after the incident and he spent the next hundred years as a Human merchant under the name of Barry Waddle. Darvin blamed Kirk for his misfortunes, and over this period his grudge grew into a fanatical hatred.

In 2373 the Cardassians agreed to return the Orb of Time to the Bajoran government. The Defiant carried the Orb back to Bajoran space; Darvin managed to talk his way onto the ship and used the Orb to throw the Defiant back into the year 2267. Before the crew realized what had happened Darvin beamed himself off the ship, intent on assassinating Kirk.

The Defiant crew had little choice but to recapture Darvin so as to minimize any changes he might cause to the timeline. Disguising themselves as Starfleet officers and civilians, they began to search both the station and the Enterprise. Darvin was eventually recaptured, and revealed that he had placed a bomb in one of the Tribbles which was infesting the Enterprise and the station at this time. Fortunately, Captain Sisko and Lieutenant Commander Dax were able to find the Tribble and beam it out into space before it detonated.

Inevitably some pollution of the timeline resulted. Most of these were minor - in several cases Defiant crew had to talk to 23rd century natives to explain their presence or gain information. However, at least two serious breaches of temporal regulations did occur. The first and most clear-cut was when Chief O'Brien, Doctor Bashir and Lieutenant Commander Worf became involved in an altercation between Enterprise crew members and Klingons who were visiting the station. This led to O'Brien and Bashir being captured by Enterprise security officers and taken to Captain Kirk for questioning. The second case involved Captain Sisko, who chose to exchange a few words with Captain Kirk before leaving the ship.

Although both of these incidents are technically violations of regulations, agents Dulmer and Lucsly recommended that no action be taken against Captain Sisko or his officers. It was also decided that the changes to the timeline were so minor as to not require any further intervention by Temporal Investigations and this event sequence has now been declared a part of the preferred timeline.