 In Stuttgart , Barton steals iridium needed to stabilize the Tesseract 's power while Loki causes a distraction , leading to a confrontation with Rogers , Stark , and Romanoff that ends with Loki 's surrender . While Loki is being escorted to S.H.I.E.L.D. , Thor , his adoptive brother , arrives and frees him , hoping to convince him to abandon his plan and return to Asgard . After a confrontation with Stark and Rogers , Thor agrees to take Loki to S.H.I.E.L.D. ' s flying aircraft carrier , the Helicarrier . There Loki is imprisoned while Banner and Stark attempt to locate the Tesseract . 
