Natasha decided she'd had enough; mustering all her remaining strength and stood as tall as she could; on the very points of her toes, she reached up and grabbed the chains above her and pulled herself up. Lifting herself off the ground she managed to grab one of her hair grips before she fell painfully back down. Thor gave her a quizzical look from across the room but chose not to question her actions. A few seconds later she'd managed to fashion a sort of key out of her hair grip.
Once again she reached up for the chains and lifted herself off the ground, in order to give herself enough manoeuvrability to reach the lock. A few minutes passed before the first cuff finally clicked open and Thor looked at her with renewed hope.
While trying to free her remaining hand, her grip gave out, and she slipped and fell. Her right wrist snapped against the jarring force of the cuff, painfully breaking her wrist. She inhaled sharply to try to ignore the pain.
Gavrok opened the door once again, slowly entering the room with a smile on his face;
"Miss Romanoff, I should have guessed"
He removed a syringe from his pocket, like the one he'd used on Clint and Steve and stuck it into Natasha's neck; rendering her unconscious once again.
"Tell me Gavrok, tell me what it is you want to know, I will tell you! Please, just let my teammates go"
"Sadly you cannot provide the information I need, however gallant your intentions"
Gavrok freed Natasha's broken wrist and carried her from the room, locking the door and leaving Thor stood alone. A moment later the room began to fill with gas and the last thought Thor had before passing out was whether his teammates and friends were even still alive...