Fearing that Darvin used the Orb of Time to alter the past to prevent his capture, the crew dress in period uniforms and investigate the "Enterprise" and K7. The ship and station are infested with tribbles, small furry creatures that reproduce rapidly. They attempt to interact with history as little as possible while investigating Darvin, but Dr. Bashir, Chief O'Brien, Worf and Odo get involved in a bar brawl between the "Enterprise" crew and a number of Klingons on shore leave. During the brawl, Worf and Odo spot Darvin and bring him back to the "Defiant". There, Darvin gloats that he has planted a bomb in a tribble to kill Kirk.