When Peter pissed a sorcerer off, Puck took revenge. He cast a spell and Beacon Hills merged with Manhattan and things got strange.
The HYDRA leaders were brought into town and caused major chaos. The police issued a manhunt for Brock Rumlow. Citizens went missing every day.
The few humans not affected by his spell reversed it before capturing Puck. Puck was given the death penalty for what he'd caused.
However, the supernatural wasn't done with the pack by a a long shot. The mage's lover Morgana wanted revenge for Puck's death. So she cast another spell over Beacon Hills. The expanded fusion of Beacon Hills and Manhattan returned with the danger being greater.
HYDRA returned with another enemy; Dr. Ivchenko, a Soviet Spy. Said spy wanted revenge on Howard Stark and was willing to take it out on his son. Stiles was put on lock-down until the danger passed.
While the spell eventually was reversed, Morgana's son escaped. Mordred was now on the loose in Beacon Hills. The town was still on edge as the lingering aftereffects ran unchecked in the streets.
Derek and Stiles were alone. They relaxed into each other's arms comfortably. Stiles kissed his boyfriend softly. He could see love in the other's eyes.
Mordred paced the floor angrily. He was getting impatient and wanted revenge. All of sudden, a light bulb switched on in his head. He smirked, lips turning up in a sinister grin soon after.
"I have the perfect idea." he declared as he grabbed a spell book. He went around his hideout grabbing the ingredients he needed to prepare.
"Nothing my parents could've done will be better than this." he vowed.