Em Planeta dos Mortos , Carmen, uma passageira no ônibus, que mostrou alguma habilidade física, conta o médico para cuidar de si mesmo. Quando o médico lhe diz isso, ela responde:
No, but you be careful, because your song is ending, sir!
O médico pergunta o que isso significa e ela responde:
It is returning. It is returning through the dark, and then Doctor...oh but then... he will knock four times.
No próximo episódio, A Água de Marte , o médico faz os golpes novamente:
DOCTOR: No, 'cos someone told me just recently, they said I was going to die. They said "he will knock four times". And I think I know what that means, and it doesn’t mean right here, right now, ‘cos I don’t hear anyone knocking, do you?
(We hear three knocks)
DOCTOR: Three knocks is all you're getting!
(The Doctor electrocutes the knocker before he can knock a fourth time)
No próximo episódio, "The End of Time", é revelado que
Gallifrey is the "it", Wilfred Mott is the "he", and the end of the song is the end of the tenth Doctor's incarnation.
O destino do mestre é abordado em outra pergunta .