The daughter of Starfleet Admiral Marcus, Carol Marcus was a physicist and advanced weapons specialist. She was used to having her father's full confidence and worked with him on all of his weapons development projects - until the advanced long range photon torpedo, which he kept from her. Puzzled and suspicious of this, Dr. Marcus boarded the USS Enterprise alongside the weapons to investigate, pretending to have been assigned to deliver them to the ship. She tried to forestall Admiral Marcus's attack on the ship in the powerful USS Vengeance, but he simply beamed her off the bridge and continued his attack.
Dr. Marcus was beamed back to the Enterprise by Khan, and survived the subsequent events. She joined the crew of the Enterprise for their historic five year mission the following year. [1] 