December 14th excerpt:

John blinked at the sudden shift in Dean’s trajectory, concern mounting as the man fell silent. He glanced at Sherlock again, whose frown deepened. “Is this– Has he ever tracked a person? ”

“Not to my knowledge,” muttered the detective in reply. His arms were crossed tightly over his chest and his eyes darted between Dean and John. Sherlock wouldn’t say it aloud, but he was looking to John for answers as much as John was to him. As a doctor, his expertise was more expansive than Sherlock’s from a medical standpoint. There was no telling what sorts of limits Dean’s ability held, or the toll it would take.