The hole you arrived here through. You can see it well from the balcony. I'll show you.
[Then she was glaring at him and asking that, and Thor sighed a little, crossing his arms over his chest, the cool metal of his armour sending a small chill through his bare arms.]
My father summoned Dark Energy to allow me to return. It took much strength from him and I was sent with the task to recover my brother, Loki, and the Tesseract.