Set right before Closing Time.
It was a normal day in the field, when Martha Jones had heard a familiar noise. She could not believe her eyes, as she saw the big blue time machine materialize right in front of her. She could not help but quickly check her hair, before the Doctor would step out of his TARDIS. New design, she noticed, and put a hand on the door. Still wood - he would never change, she thought.
She wondered what he was like, just as he stepped out. "Martha Jones!" he exclaimed and smiled widely. The young man leaned forwards, and kissed her left cheek, and then the right. "Doctor?" Martha asked, confused. "Oh yes, the box gave it away, didn't it?" Martha smiled. "It's so good to see you again!" she exclaimed. "You look great" "So do you - new face and all," "not bad" she said. The Doctor laughed. "Oh right, the face" he said, and ran his hands down his face, as a reflex.
"So, why are you here?" Martha had gone serious, a thing the Doctor had always admired her for. "Just a social call, no aliens this time" he said. Martha looked at him, her face worried before, even more worried now, but for a different reason. "When have you started doing social calls?" she asked him. "It's new" he admitted. "It's going to be quite short - a lot of other people to say goodb- hi to" he said, but Martha picked up on the goodbye. "Goodbye? Are you going somewhere?" she asked him. He shook his head. "No, I'm going to die" he said frankly, and looked down, not wanting to look into Martha's eyes.
It hurt her. How could he die? Couldn't he just regenerate again? "Why?" she asked him quietly, her eyes filling with tears. "To save time" he said. "Martha," the Doctor said, after a while of silence - giving her time to fight back the tears, like the fighter she was. "Yes?" she looked up. There were still visible signs of her holding back tears for him - her strong, brave Doctor, a man she had never stopped believing in - making the world better, never with violence, but with words. "Keep an eye on Earth for me, will you?" he asked her, dead serious, but with a smile on his face. She returned his smile and nodded. "Yeah, of course I will"
He opened his arms, and she hugged him. When they let go, the Doctor went back to his TARDIS, looked back, and said "always waste time on a hug" followed by a small wink. The door closed behind him, and the familiar wooden, blue box dematerialized in front of her.
She let go of her tears.