Ep 4. Listen

In Doctor Who (2005) season 8 episode 4, titled "Listen," the Doctor (played by Peter Capaldi) becomes obsessed with a theory about the existence of a creature that has the ability to hide itself perfectly. He believes that this creature has been with him his entire life, and that everyone has experienced it at some point. In order to prove his theory, he travels through time to different points in his own past, as well as Clara's (played by Jenna Coleman), in an effort to find evidence of the creature's existence.

Throughout the episode, the Doctor's obsession with the creature takes a toll on his relationships with those around him. Clara is particularly affected, as the Doctor's erratic behavior causes her to question his sanity and her own safety. As they travel to different points in their past, they encounter a young version of the Doctor, as well as Danny Pink (played by Samuel Anderson), whom Clara is trying to impress at the time.

As the Doctor's search continues, he becomes more and more convinced that the creature is real. He begins to act recklessly, putting himself and others in danger, as he tries to capture the creature. In one particularly tense scene, the Doctor comes face to face with the creature in question, but the appearance of a mysterious figure prevents him from studying it closely.

Ultimately, the Doctor's obsession with the creature leads him to a startling realization about his own past, and his connection to the universe as a whole. In the end, he learns a valuable lesson about the power of fear, and the importance of facing one's own fears head-on.

Overall, "Listen" is an intense and thought-provoking episode of Doctor Who that explores some of the darkest corners of the Doctor's psyche. It features standout performances from both Capaldi and Coleman, as well as some truly chilling moments that will keep viewers on the edge of their seats.