There was a giant living in Jotunheim, who was called Thrym. He had a great court and many servants, and he himself could not count gold and jewels. Great herds of cattle grazed near his abode, and there was never a lack of beer or food on his table. He only lacked a partner, with whom he could share his wealth and warm him with his body on the long winter nights. He had looked around Thrym's world for a long time for the right game, but none of the maids he met seemed worthy of this relationship. It should be added, that Thrym, how wealthy he was, so great was his self-love and high opinion of himself. Eventually, after much meditation his pride prompted him, that only one and only is worthy of becoming his wife. It was supposed to be Freyja - the goddess of love. Even though he is self-centered, the giant did not think, that she would voluntarily agree to become his spouse. So he devised a sly trick.
Once Thor woke up in a bad mood. For he dreamed, that someone stole Mjollnir from him in the night. What his horror was, when it turned out, that the hammer was indeed gone. With his hair flowing and his beard bristling, he ran all over Asgard, roaring, like an early round. The whole city of the gods in their foundations was shaking, and it seemed to people, that the sky is falling on their heads. He looked into every little slit, he asked everyone, but he found no hammer. The weapon most effective against the giants has disappeared, as if the earth had collapsed beneath it.
Thor thought for a long time, who might have stolen the hammer. He suspected at first, that it was Loki who hid him for the sake of it. More than once, he has played tricks like this. So he caught him, and having seen it, that he was not the culprit, asked for help. Loki promised to find Mjollnir, if Freyja agrees to lend him her lovely robe woven from falcon feathers. The goddess agreed and Loki, wearing a magical cloak, flew into the air, departing east.