After a long day of indulging Donna's shopping cravings, the Doctor wanted nothing more than to put away her purchases, move the TARDIS into the Time Vortex, and just listen to the comforting sound of the engines whining. Unfortunately, today would not be that day.
"It's gone!" Donna said, dropping her bags and looking around frantically. "The TARDIS - it's gone!" She frowned, peering suspiciously at the nearby houses. "Has someone gone and stolen it again?" Turning around completely, she paused. "And what are you doing?"
The Doctor had put down his set of Donna's bags and was squatting down next to where they'd left the TARDIS. Carefully, he picked something up and held it very close to his face. Squinting at it, he muttered, "Oh dear..."
That seemed to snap him out of it. Jumping up, he turned to Donna and said, "Nothing to worry about, just an old friend - well, I wouldn't say "friend" - just an old acquaintance, then. He's just borrowing the TARDIS, he'll bring it back soon."
"Borrowing the TARDIS?"
"Yeah, but he keeps his promises, and this," the Doctor said, waving around whatever he was holding in his hand, "is the best kind of promise his people can offer."
Donna squinted at the Doctor's hand. There didn't seem to be anything in it. "What's that?" She reached out to touch it, but he snatched his hand away. "Oi!"
"No, I wouldn't... do that." The Doctor cradled the thing carefully. "Humans can't quite perceive these, you see. If you actually saw it, it would burn your eyes out. If you actually touched it..."
Donna backed up, hands out in front of her. "Alright, alright! No touching. Just, what is it?"
"Well, it's sort of a... feather?" He frowned, but nodded slightly, quietly adding to himself, "It's an appropriate name for it, at least."
"A feather?" Donna snorted, putting her hands on her hips. "So, what, this acquaintance of yours is some kind of giant, alien bird?"
"No, not a bird..." The Doctor started, but a familiar whirring cut him off. He turned to where the TARDIS had been, smiling, as the time-and-spaceship reappeared. "Oh, good man! See, I told you he'd get it back alright," he added. Donna made a face, but was more interested in seeing what would walk out of the TARDIS.
What walked out was a man. Well, two men - one man with the other unconscious and slung over his shoulder in a fireman's lift. The standing man nodded at the Doctor, who returned his feather and stepped back. He tilted his head toward the sleeping man. "He your guy?"
"We believe so," the man replied. His voice was deep and hoarse, and his tone was sure. His face was covered with week-old stubble, though, and the wrinkled trench coat and crooked tie weren't doing him any favors, Donna decided. His eyes, though - that shade of blue was fairly stunning.
"Best of luck to you, then," the Doctor said. The man nodded again, and between one blink and the next, vanished. Donna may have squeaked a little. The Doctor smiled at her, then went about picking up her bags. Once he'd gathered them, he looked at her expectantly, waiting for the question that had to be coming.
"Who - what was that?" she managed after a moment. He grinned, and told her, stepping inside the TARDIS.
Donna may have squeaked a lot. She ran in after him, and shouted a question that could barely be heard over the sound of the TARDIS vanishing.
"That - that man - was an angel?"