Book One sets up the story for us by telling us what has happened before and after Odysseus left to go fight the war. It told us how his son, Telemachos, was handling the household without his father.
In the middle of Book One, it switches to the God's point of view, and shows us that not all of the God's wish Odysseus harm, so Athena begs her father Zues to send her down to help him on his journey.
At the end of Book One, we learn that Telemachos will make a call to all the men in their town to set sail to find his father. The idea was given to him by Athena.