In "The Lightning Thief," a tense moment arises when Grover informs Percy that they have a limited time to pray to their chosen god before facing danger. This highlights the urgency of their situation and the looming threat posed by Cerberus, the three-headed dog. The characters are aware they are on borrowed time, emphasizing the stakes involved in their quest.

The mention of Cerberus and the countdown reflects the perilous nature of their environment, as they must rely on their wits and faith in the gods to navigate the challenges ahead. This interaction showcases the blend of humor and tension throughout the story, a hallmark of Riordan's writing style.