The person was trapped in the house's attic. The Twelfth Doctor helped this person out by giving them access to four security cameras in the house, allowing the person to watch the Angels and stop them from getting to the attic.
The first camera was located in the house's basement. The second was located in a corridor. The third was located in the kitchen. The fourth camera was in the nursery, which had a rocking horse in it.
The Doctor sent his TARDIS to the attic and the person was able to get in using a key which the Angel from the corridor had. The TARDIS left the attic, leaving all four Angels quantum-locked. (GAME: Don't Blink)