This book recounts the final part of the fortieth day, its – miraculously prolonged – night, and the beginning of the forty-first day (cf. Appendix A); it brings the long-delayed reunion of Odysseus and Penelope, but also prepares for the final scenes of the Odyssey (the confrontation with the families of the slain Suitors: 117–52, 362–3; and Odysseus' reunion with Laertes: 359–60).

The reunion consists of the following parts: recognition of Odysseus by Penelope (1–246), which is interrupted by a scene in which the departure of Odysseus and his companions for the country is announced (117–65); the couple's first conversation, which discusses the future (247–87); their love-making (288–99); their second conversation, which centres on the past (300–42a); and sleep (342b–348). It is followed by the departure of Odysseus and his companions (349–72).

The theme of the reunion of husband and wife is underscored by the narrator through his use of periphrastic denomination †: more than in any other book, Odysseus is referred to as πόσι(2, 86, 181, 239), Penelope as ἂλοχος (165, 182, 232, 165, 182, 232, 247, 346, 349).