The Doctor takes Amy for a visit to the opera in Paris, 1858, where young women become magnificent singers under the tutoring of Monsieur Valdemar. In the shadows, screams mean only one thing — death.
Part 1: The Screams of Death
In 1858 Paris, Cosette visits the residence of Monsieur Valdemar to audition for a role in the opera. Despite her lacking the talent to carry a tune, Valdemar tells her he believes he can help her. He tells her to look into his eyes, which begin to glow green...
Several months later, the Doctor takes Amy for a night at the opera. Cosette is performing, and Amy marvels that she's never heard such good singing. The Doctor notices that she has a reduced blinking rate, as though she was in a hypnotic trance. Outside, Valdemar escorts Cosette away as a man, Louis, begs her to see him. The Doctor deduces that he is her ex-boyfriend. In a café, Louis tells the Doctor and Amy that they were engaged to be married before she went to see Valdemar, and now she acts as if she doesn't even know him. They are interrupted by a scream, and rush outside to find the dead body of a homeless man with blood around his ears. They realise that the scream was not his but a young woman's, but are forced to flee by the arrival of the police.
Later, the three break into Valdemar's house through the roof, to find a room full of girls from the opera in an artificially-induced catatonia. They also find a DNA sequencer, "a machine for decoding genetic inheritance". Valdemar returns and they all hide. He awakens the girls, who now have green glowing eyes and a green gas being released from their mouths. He gives them a list of names of people to locate and obtain a genetic sample of. When he selects his victims, they will sing them to their deaths. The girls then fly out into the night to obtain the samples, and Valdemar reveals that he knows of the Doctor, Amy and Louis's presence. The Doctor asks him how the levitation works, but he decides that they have already seen too much and cannot be allowed to leave. He finally awakens Cosette, who he commands to sing to them all. She lets out a deathly screech, and the Doctor, Amy and Louis futilely cover their ears.
Part 2: The Legacy of Blood
In Salzburg, 2098, Eldritch Valdemar is found guilty of treason, murder, mental domination, and perverting the human form by genetic manipulation as leader of the eugenic cult. He condemns his followers, who sold him out in return for their freedom. He declares that he will have his revenge, before apparently being executed.
Back in 1858 Paris, the Doctor, Amy and Louis awaken chained to a wall. Valdemar commands Cosette to obtain a genetic sample from each of them by kissing them. Louis sees Valdemar's list of targets and realises that it's all the same four surnames. The Doctor realises that he is trying to get rid of these people's descendants by preventing them from ever having been born. Valdemar admits that he is trying to prevent the treachery of those he trusted most by erasing them from time. He needs the genetic samples from them to ensure that they aren't his ancestors, and that he does not accidentally prevent himself from existing as well. He believes that at the point of his execution he was miraculously transported back through time. As the opera girls return he leaves them to decode their genetic samples. Louis realises that the Doctor and Amy are from the future, as Amy uses a hairpin to pick the locks. They go back upstairs, only to be caught yet again by Valdemar. He declares that the Doctor is not of this world and Amy is not of his heritage, and commands Cosette to sing them to their deaths. However, Louis threatens to poison himself, realising that he must be one of Valdemar's ancestors. Faced with this threat, Valdemar leaves to murder the ancestors of his enemies, but Louis manages to stop Cosette from going with him.
The Doctor then uses Cosette to follow him to Notre Dame, where he tells Valdemar that he cannot change his own past. When Valdemar decides to instead eradicate all obstacles starting with him, the Doctor uses his sonic screwdriver to set off the bell. This frees the girls, who turn on Valdemar. Angry for his deceit and betrayal, they drive him over the edge, and he falls to his death.
Later, in the café, the Doctor and Amy ensure that Cosette is back to normal (along with her singing abilities, or lack thereof), then return to the TARDIS. Louis thanks them for their help, and watches their dematerialisation. Shocked, he turns to Cosette, but she has vanished. Chiyoko watches and smiles from the shadows...
- The Doctor identifies this period as the Second French Empire.
People from the real world
- Amy jokingly tells Valdemar that she is heavily into science fiction. She gives Jules Verne as an example of a science fiction author.
- The Doctor states that his top hat is cool. He previously referred to clothing items being cool. (TV: The Big Bang, COMIC: The Golden Ones)
- The Doctor reminds Amy of when he let her get into trouble in Venice. (TV: The Vampires of Venice)
- Chiyoko, the Japanese girl seen with Axos in COMIC: The Golden Ones, witnesses the Doctor and Amy's departure.