As the story opens we see the palace of Odysseus overrun by suitors who are seeking his wife's hand. They, along with many others, believe that perhaps the hero is dead, and the time has come for his Penelope to remarry. The "Suitors" have taken advantage of the Odysseus' absence to feast themselves at the expense of his estate. To this point Odysseus' son Telemachus has been too young to intervene, or even perhaps to fully understand what is happening around him.
Just as the poet must ask for divine assistance to begin his art, so in the Odyssey the young Telemachus needs the prompting of a god (Athene) in order to begin his task. Athene comes to him, as the gods often do, in disguise. This is an important theme for the book as a whole. Odysseus himself will come in disguise, as if in imitation of the visits of the gods. The themes of disguise/discovery or hiddenness/revelation will be part of the story to the end. And such themes can raise interesting questions. Why must the gods so often appear in disguise? Why can't they be discerned immediately?
One partial answer is given in book I: the disguise of the gods reveals the true character of mortals. We see the disguised Athene coming to the palace of Odysseus, where the Suitors are in full feast. It is only Telemachus (I.114) who offers the virtue of hospitality to the new stranger in their midst. Thus the disguise of the goddess is designed to show us the character of Telemachus. He is contrasted with those around him; he is a good man living among the shameful.
Soon the conversation turns to Odysseus. Athene and Telemachus speak back and forth of the missing hero, and the goddess assures him that "he will think of a way to return - he is endlessly resourceful". (I.205) Here we have the consummate Homeric adjective for Odysseus. We know from the outset that Odysseus will find a way - but what is the way? And how will he show himself to excel in this area of "resourcefulness", this virtue which is neither simply that of the warrior not the debater? Athene puts it into the mind of Telemachus to plan a journey of his own in order to find news of his long lost father. He is invigorated with courage from the goddess. And so the homeward voyage of Odysseus will begin with the outbound voyage of his son.
Homer: The Odyssey intro
Homer: The Odyssey pt 1