Pearl was an accomplice of the Ghostmaker. She was also involved in a romantic relationship with him.
Pearl enjoyed bathing in, smelling and tasting water. She travelled with the Night Travellers in the Joshua Joy Travelling Show from the late 19th century onward. The Ghostmaker described her as the "closest thing you will see to a living mermaid" and said she was as capable of living on the ocean's floor.
When film and cinema killed off the travelling shows, Pearl and the other Night Travellers became trapped on film. However, Pearl and the Ghostmaker were able to escape in the 21st century when a roll of film with the Night Travellers on was played at the Electro. The duo set about taking away the last breaths of victims in the area, yet leaving them alive as an "audience". They collected the breaths in a silver flask.
When Pearl decided that the other Night Travellers should be free as well, she and the Ghostmaker stole the film of the Night Travellers from Jonathan Penn's flat. They then returned to the Electro and played the film, releasing the other Night Travellers. However, Jack Harkness filmed them all on a film camera and exposed the camera's untreated film, destroying them. Though Pearl and the other Night Travellers were apparently destroyed, Jack feared that they could return through other lost rolls of old film that contained them. (TV: From Out of the Rain)