You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Doctor_Who

Context:
Following the series revival in 2005, Derek Jacobi provided the character's re-introduction in the 2007 episode "Utopia". During that story the role was then assumed by John Simm who returned to the role multiple times through the Tenth Doctor's tenure. As of the 2014 episode "Dark Water," it was revealed that the Master had become a female incarnation or "Time Lady," going by the name of "Missy" (short for Mistress, the feminine equivalent of "Master"). This incarnation is played by Michelle Gomez.

Question:
What was the 2007 episode that featured the Master's return?

Utopia