When Gilgamesh gets back to Uruk, he does what anyone would do after making a journey to distant lands and doing battle with a horrible monster: he has a bath.
When that's done, he puts on his nicest duds, and gets ready for some royal chillaxin'.
While he's hanging out in his finery, he catches the eye of the goddess Ishtar. She instantly develops a serious crush on him.
Ishtar calls out to Gilgamesh, and asks him to take her as his wife. She promises him all sorts of crazy riches if he will only accept her offer.
But Gilgamesh doesn't take the bait. First of all, he says he's afraid of becoming Ishtar's husband because she's probably super high-maintenance. (Because, you know, she's a goddess and all.)
Second of all, Gilgamesh doesn't like Ishtar's track record. According to him, Ishtar has a long history of picking up various men (and animals), loving them for a while, and then abandoning them to horribly painful fates.
Ishtar doesn't like that one bit. She can't stand being accused of having killed her former lovers. So what's she going to do about it? She is going to kill Gilgamesh, that's what!
Ishtar goes up to the heavens to speak to her father, the god Anu, and her mother, the goddess Antum. "Daddy," Ishtar says, "Can I borrow the Bull of Heaven tonight? I just want it to kill Gilgamesh, then I'll bring it right back, I promise."
"Now, now dear," says Anu, "don't you think you're overreacting a bit? After all, you're the one who provoked Gilgamesh in the first place…"
"NO!" says Ishtar, "I have to punish him! Give me the Bull of Heaven now! And if you don't, I'll go down to the underworld and release all the dead people so that they can take over the earth. Then you'll be sorry!"
When Anu hears these words, he starts to give in. But, like any good father, he first wants to make sure that Ishtar is ready for the responsibility. "You know, sweetie," he says, "if you unleash the Bull of Heaven, it will destroy the land of Uruk, and the crops won't grow for seven years. Have you collected enough food for the people and animals for the next seven years?"
"Of course, Daddy," Ishtar says. "Don't you trust me?"
With that, Anu gives Ishtar the keys—that is, the nose-ring of the Bull. Ishtar leads the Bull of Heaven down to the earth.
Once the Bull reaches Uruk, it goes on a rampage. The first time it stamps its foot, a huge crevice opens in the ground, and 100 warriors of Uruk fall into it. The second time it stamps its foot, another giant crevice opens up, and 200 warriors fall into it. The third time it stamps its foot, another giant crevice opens up, and Enkidu falls into it up to the waist.
But Enkidu thinks fast: he jumps out of the pit and grabs the Bull by the horns. Enkidu calls out to Gilgamesh for help. Gilgamesh stabs the Bull in the neck, killing it.
After killing the Bull of Heaven, Enkidu and Gilgamesh rip its heart out and present it as an offering to Shamash, the sun god.
In the meantime, Ishtar climbs up onto the wall of Uruk. She is seriously bummed out that she's totally wrecked her dad's Bull of Heaven. (The Gods: they're just like us.)
Obviously, she blames Gilgamesh.
When Enkidu hears this, he does something shocking: he tears off one of the Bull's back legs and throws it in Ishtar's face. Then he says that he would tear her to pieces too, if he could.