Duquesne went to examine the Collection of Necessary Secrets at the Vatican for the Directory. She was given a tour of some of the exhibits by Cardinal Catilin. She was then sent to America to investigate the strange occurrences in Woodwicke. When she found the TARDIS, its de-rationalised state allowed her to enter by walking through the outer plasmic shell.
Once inside, she met Chris Cwej. As the TARDIS de-rationalised further, they were drawn into an imaginary Paris. Reminded of all the things she had seen which had no rational explanation, she was convinced to accept the irrationality of the universe. This allowed the Carnival Queen's return from banishment, and she used Marielle as her interface with reality.
Later, when Chris' decision to side with order exiled the Queen again, Marielle was freed from her influence. Afraid she had been contaminated by what had happened in Woodwicke, the Directory planned to retire her. When she found this out, she went into hiding with Daniel Tremayne. The two of them went to France to find other psychics like them. (PROSE: Christmas on a Rational Planet)