Hes Missing - Torchwood contacts The Doctor telling him Jack is missing and has been for a couple of days. The Doctor becomes worried and tries to track Jack down. When he finds Jack. Jack appears to have lost some of his memories and doesn't know who the Doctor is.
The Doctor had been walking alone through London. He had nobody with him and it made him feel lonely. He knew he could always ask Jack, but he didn't want to pull Jack away from Torchwood when he knew he had responsibilities even if Jack would probably be ok with it. He sighed and continued to walk around. The Doctor was unaware what had happened to Jack, he though noticed Torchwood was trying to contact him and picked up the phone he had, it was Martha's old phone that Jack or even Martha had contacted him on.
"Jack?" he said expecting it to be his old friend, but instead it was Torchwood and they were telling him Jack was missing.
"Hes what?" The Doctor sounded worried and continued speaking with them "Alright.. I'll go look for him," He couldn't believe Jack had been missing for a few days and wondered if he was ok. He quickly ended the call and literally ran back to the TARDIS. He knew he should get searching soon as possible. He started up the TARDIS and started flying it.
"ALLONS-Y!!" He shouted.