During the mid-2250s, the Endeavor was enroute to Starbase 14, when she mysteriously disappeared in the Theta Eridani system. The starship was eventually discovered by the USS Enterprise in 2273, and they learned that the Endeavor's crew had been killed when the combined consciousness of a lost transporter research team took control of the starship's systems. (TOS comic: "Experiment in Vengeance!") In a couple of panels in the comic, the registry number of NCC-1705 is displayed on the Endeavor's hull.