"The Lost Hero" by Rick Riordan is the first book in the "Heroes of Olympus" series, a spin-off of the "Percy Jackson & the Olympians" series. The novel follows three demigods—Jason Grace, Piper McLean, and Leo Valdez—as they embark on a quest to free the Greek goddess Hera and prevent the awakening of the Earth Mother, Gaea.
One crucial event in the story revolves around Jason's memory loss. At the beginning of the novel, Jason wakes up on a school bus with no memory of his past. This creates a sense of mystery and urgency, as Jason's lost memories hold the key to the unfolding prophecy and the fate of both Greek and Roman demigods. Unraveling the mystery of Jason's identity becomes a central focus of the narrative, driving the characters forward in their quest.
The second pivotal event is the discovery of the "lost" demigod, Percy Jackson, who has been missing for several days. Percy's absence is a source of concern for both Camp Half-Blood and Camp Jupiter, the Greek and Roman demigod camps respectively. The revelation of Percy's whereabouts and his connection to the unfolding prophecy significantly impacts the quest, as it brings together the Greek and Roman demigods, who must unite to face the looming threat of Gaea.
These two events—the mystery of Jason's lost memories and the discovery of Percy Jackson—form the backbone of the narrative, propelling the characters into a dangerous and interconnected world of gods, monsters, and prophecies in "The Lost Hero."