Chukwudi Iwuji

Four envelopes, numbered 2, 3 and 4, each containing a date, time and map reference, unsigned, but TARDIS blue. Who sent them? And who received the missing number one? This strange summons reunites the Doctor, Amy, Rory and River Song in the middle of the Utah desert and unveils a terrible secret the Doctor's friends must never reveal to him.

After learning that a member of the inner circle of the terrorist organization "Boko Haram" has fallen ill with a deadly virus, Elizabeth formulates a plan to leverage his weakness and release a group of schoolgirls they are holding captive. Also, Henry gets new information on the terrorist Jibral Disah that leads his team closer to pinpointing his location.

Jocelyn shares her very personal story of hearing loss when she finds herself face-to-face with the adversary responsible for the bomb explosion that changed her life forever. Meanwhile, the team works together to take him down and infiltrates an illegal, underground operation that has deadly consequences when not everyone comes out alive.