[[Eleventh Doctor|The Doctor]], [[Amy Pond]] and [[Rory Williams]] land in a pea-souper of smog in [[London]] [[1885]] on Threadneedle Street EC2, home to the [[Bank of England]]. They are alerted to a powerful explosion, but when they get there everyone seems oblivious to the damage and carries on with their everyday lives.

Traces of [[carbonite]] in the air reveal an alien presence at work. Another explosion from down in the vaults attracts the travellers' attention and they run to investigate. There appears to be no sign of damage to the vaults and no-one around except a kindly old flower seller. Amy is concerned and tries to coax the old lady back up the stairs to safety. However, the Doctor suddenly turns on the old woman and throwing the flowers aside, uncovers a traffic-calming measure from the Aldebaran Astrobahn, a small device that pacifies space pilots so they can fly safely. The device is being used to cover up the raid on the bank.

The old woman suddenly changes into an [[Alien bank robber (Reality Cheque)|armed alien bank robber]], who grabs Rory. Before the robber can fire his gun, the Doctor reactivates the reality check device and points it at the robber to give him suggestions that he takes – that he doesn't want to fire his gun, that he doesn't want to be a criminal, and that all the happiness he will ever need can be found in a single flower!