The Summer I Turned Pretty has stuck pretty close to Jenny Han's book series - until season 3 when the show introduced some of the biggest onscreen changes. Based on Han's three novels, The Summer I Turned Pretty is focused on a love triangle between Belly (Lola Tung), Conrad (Christopher Briney) and Jeremiah (Gavin Casalegno). The current season is slated to be the show's last as Belly finally makes a decision between the brothers.