The beginning of the episode depicts the Tenth Doctor composing Ode to the Universe: a symphony based on the "music of the spheres"—an aural representation of the Universe's gravity patterns. During the composition, a Graske teleports into the TARDIS to warn the Doctor about the imminent opening of a portal within the TARDIS. The Doctor approaches the portal, linking the TARDIS to the Doctor Who Prom at the Royal Albert Hall. He briefly converses with the audience and then conducts the orchestra in a performance before he realises the Graske has escaped into the Prom with his water pistol. He forces the Graske's return by "reversing the polarity of the neutron flow" and banishes him from the TARDIS, to the other side of the galaxy. At the end of the episode, he tells the viewer that the music of the spheres encompasses everyone, and that "Everyone's got a song inside them. Every single one of you."

18世纪英国，博士发现了另一个博士，失忆的博士。

博士误以为是处于另一条时间线上的自己，于是隐瞒身份，暗中帮助失忆博士。

这里，博士发现了大量赛博人，而他们想找到一个拥有强领导力的人，做他们的首领...