The Doctor decides to break in to the most dangerous bank in the Cosmos.
Clara's second date is interrupted by the ringing of the phone in the TARDIS while it's in her living room.
The Doctor and Clara find themselves in the world's most impenetrable bank with an order to rob it. The Bank is watched over by Mrs. Delphox and The Teller. He's not a bank teller, but a a being that can sniff the truth. He must be very worrisome even to Mrs. Delphox because he's bound in an orange jumpsuit. The Teller also wipes the minds of people -- right out of their heads.
To save his friends and family from coming to any harm due to his misdeeds, Psi erased his memory of them all. Clara finds that both sad and commendable.
No one can touch the shapeshifter because as soon as they do, she turns into them. As she says, it comes in handy for truth because you can't tell a lie to someone looking at you out of their own eyes.
I thought Mrs. Delphox was the bad guy, but perhaps it's the architect. He sent them back in time to the moment a solar storm hit so they could infiltrate the bank's security systems when they were most vulnerable.
The Doctor finally puts it all together. Mrs. Delphox was a clone of a woman who was dying and it wasn't a bank heist but a rescue mission -- The Teller's mate was being held captive and The Doctor and Clara took them to their home world.