Solar storm

A solar storm occurred on the planet which hosted the Bank of Karabraxos, the most secure bank in the universe. The Twelfth Doctor received a phone call from an elderly and dying Madame Karabraxos, telling him about her many regrets and sending him and Clara Oswald on a mission to rescue the Teller and its mate from the bank prior to the storm's arrival. (TV: Time Heist)