The Doctor was relived when the young girl took his hand without much hesitation and he led her to stand beside him. The night guard continued to keep eye contact with the Time Lord. 

"You can give up the act," The Doctor said sternly, tightening his grip on the girls hand. "No wonder my TARDIS picked up a signal here, you certainly don't belong here, do you?" As the Doctor questioned the man, he began to growl. A low threatening growl that began to get louder and louder the more the Doctor spoke. "What are you doing on Earth?" 

Suddenly, the man seemed to stop his menacing growling and before the Doctor could say anything more, the human figure of the male began to change. Even through the darkness of the corridor, it was clear to see the mans skin beginning to crawl and change. His once pink skin began to turn green, and the man pilled on pounds of green flesh, growing long clawed hands and a snout that replicated a lizard snout. Without trying to draw to much attention, the Doctor leaned over to the girls ear and whispered into her ear. 

"On the count of three, I want you to run with me. Don't let go of my hand, you got that?" He told her firmly. "You ready? One...two...three...RUN!"