ARK-7 was a space station operated by the United Federation of Planets in the mid-23rd century.
In the 2260s a team of 17 scientists led by Doctor Carol Marcus were working on the station on a highly classified project to uncover the mysteries of life. The team eventually developing a device called the cradle, which contained scores of microscopic life forms. But during the course of this they also accidentally created a virus which was deadly to Vulcanoid life forms.
When the Romulans discovered this, they believed the virus to be a weapon to be used by the Federation to commit genocide against the Romulan people. The Romulans responded by sending a force of 10 Romulans lead by Centurion Preax to board the station and take the scientists prisoners.
The crew of the USS Enterprise arrived to investigate the situation. Upon boarding the station, Spock was infected with the virus, which made him seriously ill. The crew of the Enterprise worked rapidly to find a cure for the virus. The Enterprise team cured Spock and the Romulans on board the station, and then freed the Romulan captives. Satisfied that the creation of the virus was an accident, the Romulans left Federation space peacefully. (TOS video game: 25th Anniversary)