Donna's (Catherine Tate) world falls apart, and there's no sign of the Doc (David Tennant). Who should turn up to her rescue but a blonde lady thought to have been trapped in a parallel universe ...
Yes, it's Rose Tyler (Billie Piper)!
The companions team up - but can they save the world from 'the darkness'?
Of course we all want to know whether Rose and the Doc get it together, but Billie insists there's more to their characters than that.
She told the Radio Times: "The Doctor has turned her life on its head for the better.
"She found this person who has made her celebrate life and humanity, and said: 'Look, you should have this zest for life because here are the reasons why it's great.
"Sometimes you need someone to shake you and make you look at what's going on around you and make you want to be a better person."
Aw. Rose will also join forces with Martha (Freema Agyeman) in next week's finale. "The tragedy (of the Doctor and Martha's relationship' was that she fell quietly in love with him," said Who reviver Russell T Davies.
Will sparks fly between Martha and Rose? Who can say, but Freema simply says that, "there's a wonderful moment that just emphasises how much he needs them all in different ways and how they are very much part of a team within his life."
Sounds like a beautiful thang!
Tune in this Saturday, 21st June, 6.40pm. BBC One.