Laura was a nursing home attendant who cared for the Master during the final days of his life
Biography
When the Master died, Laura encountered the Doctor and his friends Tegan Jovanka and Turlough. she was then drawn into the world of the Time Lords when many patients in the nursing home fell into a deep coma. Laura teamed up with Tegan to investigate and later discovered that the Master was not dead and was not the man she thought he was. After discovering he was behind the deaths of the nursing home residents, she worked to help the Doctor defeat him.
She later discovered the nursing home wasn't real and was designed to trap people. A devastated Laura then worked to help the Doctor defeat the Master, freeing her from his powers. (ST: The Velvet Dark)