At the beginning of the novel Harry, Ron, and Hermione attempt to spend a semi-normal summer, celebrating weddings and romances. However, the illusion of normalcy is soon smashed and they must begin their journey to destroy the Horcruxes, reservoirs of power that keep Voldemort alive, so that during the final battle he can be killed once and for all.
Along the way Harry learns who his real friends are. Hermione knows what is at stake and never wavers but Ron has a moment when he leaves the group, the stress being too much for him. In the end most of Harry’s classmates who have stood beside him at some point during the earlier novels continue to support him until the very end. This is the main lesson: love and support truly are some of the most powerful emotions that can be found on this earth.
The end of the series is very powerful, with several important characters being killed in the heat of the battle. Major secrets are revealed, romances blossom, and the epilogue explains what happens to Harry, Ron, and Hermione in the future.