Seppi is in for a real heatwave this time! The first hot weeks of the year have arrived, and as the temperature rises outside, Seppi's enthusiasm for school and annoying teachers plummets. But when the new school mascot becomes a victim of a crime, Seppi suddenly finds himself the main suspect in a real criminal case, which puts him under a lot of pressure. Naturally, he doesn't want to let that slide, so he sets out between the swimming pool and school stress to uncover the true culprit. But is he really as innocent as he wants everyone to believe?.