Since the end of the 2nd season of Agents of SHIELD on ABC, Agent Gemma Simmons, has tampered with a dark misty force captured earlier in the season by the team from a trip to Asgard. It could have been some new weapon of the infamous Frost Giants'. For this reason, she has gone awall because of this force in the end of the final episode of the 2nd season.
Thus, ex-agent Simmons has become a female Frost Giant enstranged on the icy planet home to the Frost Giants and the other SHIELD agents finding this out how to cure Simmons or help her master her powers for good, not evil. To do so, they must receive the aid of Thor (Chris Hemsworth).
Will Simmons be saved or cursed to remain with her icy powers forever? Find out in the 3rd season of Agents of SHIELD when it returns to ABC this fall.