The Days of Terror was a period of four days during the Tethyrian Interregnum between the end of Tarsakh and beginning of Kythorn in 1367 DR and refers to the events that happened in Zazesspur during this period.
Firstly, child slavers were discovered in the caves beneath the city and they were removed. Secondly, the Darkling armies were released onto the streets by fell forces. Thirdly, the ruling Council was almost entirely wiped out when its members were murdered by their own children, who were affected by evil. Finally, Baron Faneuil Hardisty and the local Church of Ao, including its high priest, were all exposed as frauds and veiled agents of evil.
Most of these events were instigated by the deepspawn called The One Below and its minions. Zaranda Star and her companions, Star Protective Services, brought the Days of Terror to an end on Mirtul 3, 1367 DR.