The Doctor (David Tennant) and Martha (Freema Agyeman) arrive in New York City in 1930, in the depths of the Great Depression. They find a newspaper article about people disappearing and investigate a Hooverville in Central Park. They meet Solomon (Hugh Quarshie), the leader, and Mr. Diagoras (Eric Loren), who is there to hire workers for sewer construction. The Doctor, Martha, Solomon, and young Frank (Andrew Garfield) all sign up. Working to clear a collapsed sewer tunnel, they explore, and the Doctor finds a mass of alien organic matter, which he takes to analyze. They run into a group of pig slaves and run, but Frank is captured.

Escaping up a ladder, the Doctor, Martha, and Solomon find themselves in a theatre, where they meet a showgirl named Tallulah (Miranda Raison), whose boyfriend Laszlo (Ryan Carnes) has disappeared. The Doctor creates a matter analyser using equipment in the theatre while Martha consoles Tallulah. Martha sees a pig slave and pursues it into the sewers, where she is captured. The Doctor and Tallulah follow and discover that the pig slave is Laszlo. They also find a Dalek, proving that the Doctor is right about the organic matter being from the planet Skaro.

They follow the Daleks, which Laszlo tells them are responsible for the disappearances. The victims are made into pig slaves or used for other experiments. Tallulah returns to the theatre, but the Doctor and Laszlo sneak into the Empire State Building construction site and find Martha and Frank. They encounter the Cult of Skaro—the last four Daleks in existence. The Doctor hangs back and watches while the Daleks tell Martha they want to meld the human and Dalek races. Dalek Sec (voice of Nicholas Briggs) becomes the first such, merging with Mr. Diagoras to become a human-Dalek hybrid. To be continued.

Tallulah was based on Jodie Foster’s character of the same name in the film Bugsy Malone. The music includes Gershwin’s Rhapsody in Blue and Irving Berlin’s Puttin’ on the Ritz. Some of the story was filmed in New York, but most of it in parts of Wales. Miranda Raison (Tallulah) played the Sixth Doctor’s companion, Constance Clarke, in an audio version of Doctor Who. Andrew Garfield (Frank) was of course Spider-Man in the Amazing Spider-Man movies. Diagoras is named for the 5th Century Greek poet Diagoras the Atheist. Real New Yorkers would know you can’t see the Empire State Building from Central Park at that angle, if at all. The story has flavours of The Island of Doctor Moreau, Frankenstein, and The Phantom of the Opera, and carries some of that over-the-top Gothic horror baggage. It was generally well received, though some complained about the American accents and the American stereotypes, which are fairly common in Doctor Who.