"Instead of the cross, the Albatross / about my neck was hung" (lines 141-142).
"Each turn'd his face with a ghastly pang, / And cursed me with his eye" (216-217).
The Ancient Mariner stops a Wedding-Guest on their way to a wedding. Though he protests, the Wedding-Guest is forced to listen to his story. He starts his story by explaining how him and his shipmates were caught in a big storm that brought them to a cold and icy ocean. They were saved by an Albatross that allowed their ship to be moved to safer water. The sailors saw it as a good omen, but then the Mariner killed it.
"The Albatross fell off, and sank / Like lead into the sea" (lines 291-292).
The other sailors were angry with the Mariner for killing their good luck charm, but after they remained in safe waters, they realized the Albatross was probably not good luck at all, so they accepted its death. They sailed in calm waters for a while, but then the Albatross begins to be avenged. The sailors are stuck in the middle of the ocean and are unable to drink the water that surrounds them. The other sailors place the Albatross around the Mariner's neck to place full guilt on him.
"Quoth he, 'The man hath penance done, /And penance more will do'" (lines 409-410).
The Mariner sees a ship coming and drinks his blood in able to call out for them. The ship happens t be Death and Life-in-Death. They play a game of dice for the sailors and Life-in-Death wins, killing every single sailor on the ship except for the Mariner.
"He'll shrieve my soul, he'll wash away/ The Albatross's blood" (lines 513-514). "He prayeth well, who loveth well /Both man and bird and beast" (lines 613-614).
The Mariner tries to pray but is unable to. He was cursed to endure the glares of his dead shipmates. He marvels in the beauty of the water snakes in the ocean and is able to bless them unaware. This allows the Albatross to drop from around his neck and into the sea.
His dead shipmates rise from the dead with the help of angelic forces. While they are sailing, the Mariner hears two voices deciding whether or not he has completed his penance. One decides that even though he has lived a curse, he will continue to live that curse for killing the Albatross.
Part 6: The spirits propel the ship back to the Mariner's home where his penance begins again. After the angelic forces are removed from the dead shipmates, the Mariner sees a Pilot, the Pilot's boy, and a Hermit rowing in a boat and believes that the Hermit can help him. Part 7: The Mariner's boat begins to sink and he is saved by the Pilot. He finishes his story to the Wedding-Guest and warns him to love all of the world's creations.