 Fearing that Darvin may be attempting to assassinate Kirk , the crew dress in period uniforms and investigate the Enterprise . They attempt to interact with history as little as possible whilst investigating Darvin . The crew does not initially recognize the Klingons of the time period , and when Worf ( Michael Dorn ) is asked about the difference in appearance , he replies that the matter is not discussed with outsiders ( this is further expanded on in the Star Trek : Enterprise episodes " <unk> " and " <unk> " ) . Doctor Julian Bashir ( Alexander <unk> ) and Chief Miles O 'Brien ( Colm <unk> ) get involved in a bar brawl between the Enterprise crew and a number of Klingons on shore leave . Captain Kirk disciplines them on the Enterprise alongside Chief Engineer Montgomery Scott ( James Doohan ) and Ensign Pavel <unk> ( Walter Koenig ) . Bashir and O 'Brien notice that the ship is covered with tribbles . Lieutenant Commander Worf ( Michael Dorn ) and <unk> ( René <unk> ) trail Darvin as he returns to the Defiant . There , Darvin admits that he planted a bomb in a tribble to kill Kirk . 
