Sandi Costello

 was first mate aboard the land ship the Beagle. She was one of an expedition financed by that followed the alien presence in the psychic Lady Takashi's dreams to the moon of Titan. When the Twelfth Doctor and Bill was caught in the ship's wake, Sandi saved them by throwing a lifebelt at them, and they were brought aboard. Later, when the ship changed its buoyancy and sailed on the methane river, the Beagle approached a cavern, and Lady Takashi said that they were close. They found a Garden with a breathable environment and artificial gravity. The team was attacked by the Garden's robotic Keeper, but the Doctor stopped it. Afterwards, the plants in the Garden intended to consume them. (COMIC: The Soul Garden)