The Doctor put a hand on Jo's arm.

"Nothing," he said. "It's not there for me, it's---"

The moment he looked back, though, he saw Donna. Standing there, in a silly holiday hat, looking sad. She was transparent, obviously unreal, but something about the way she stood there made it almost irresistible to go towards her.

"I can see it," he said. "Looks like an old friend of mine. You have to fight it. We can do it."