The premiered episode of Season 3 of "The Summer I Turned Pretty" kicks off with Belly embarking on her college journey at Finch College, driven primarily by her desire to stay as close to Jeremiah as feasible. Her family accompanies her to drop her off, and amidst this, we catch a glimpse into Taylor's tumultuous relationship with Steven, who attends the same institution.
As Belly sets up her dormitory room, Laurel drops a bombshell by revealing she video-called Conrad and caught a glimpse of a girl named Agnes by his side. Undeterred, Laurel pushes Belly to embrace new experiences and discover different facets of herself.
The narrative then makes a captivating leap forward to three years hence. Jeremiah stands on the cusp of graduation, and Belly is consumed by anxiety about facing this milestone without him by her side. A call from Laurel informs Belly of her plans to organize a dedication ceremony for Susannah in Cousins, an event that necessitates speeches from both Jeremiah and Conrad.
Elsewhere, Conrad is thriving in medical school, confiding in his therapist about the anxieties that linger as he ponders his return to Cousins. As Belly and Jeremiah stroll through the vibrant campus, a revelation unfolds: Belly, sidelined by a knee injury, has temporarily hung up her volleyball spikes in favor of delving into the world of sports psychology.
Meanwhile, Steven finds himself immersed in an internship at Adam's company, where his professional life contrasts sharply with his personal entanglements. After clocking out, he rendezvouses with Taylor, only to be caught off guard by an unexpected visit from Belly, prompting him to duck out discreetly. It transpires that Steven and Taylor are both involved with others, yet they find themselves in a clandestine affair, cheating on their respective partners.
During a study session filled with laughter and camaraderie among the girls, Belly receives thrilling news: she has been taken off the waitlist for a prestigious study abroad program, destined for Paris during her senior year! Thrilled to share this joyous tiding with Jeremiah, Belly's excitement dims when she encounters him in a melancholic state. He reveals a bitter disappointment—due to a change in his major, he has inadvertently missed out on crucial "core classes," jeopardizing his graduation prospects.
Consequently, he'll be extending his college stay by an additional semester, a circumstance that deters Belly from confiding in him about her upcoming trip to Paris. As Belly shares updates about Taylor, a revelation dawns upon her: Steven and Taylor are indulging in an illicit affair, betraying their respective partners.
At medical school, Conrad and his friend Agnes receive exhilarating news; they've been chosen for a prestigious summer clinic position. However, the program commences imminently, rendering it impossible for Conrad to attend his mother's dedication ceremony at Cousins. He breaks this news to Laurel, who empathizes with his dilemma.
Upon her return, Taylor discovers Steven still present in her room. Eventually, he spends the night. The following morning, Steven inquires if they should repeat their indiscretion that evening, but Taylor swiftly declines. In a hurry, she dashes off to an event known as Finals Freakout, a weekend-long festivities where students unwind through games amidst the looming pressure of their final exams.
At Finals Freakout, Belly endeavors to lift Jeremiah's spirits. Taylor encourages Belly, despite their sorority differences, to participate in the games. Amidst Jeremiah's game, Conrad's call interrupts, with Belly answering the phone only to hear Conrad hastily promise a callback before abruptly ending the conversation.
Later, as Belly and Jeremiah set off for dinner with Steven, Adam phones Jeremiah, lambasting him over a botched college course arrangement that will incur additional expenses. Disheartened, Jeremiah suggests Belly proceed without him.
During dinner, Steven brings up how Jeremiah can often be impulsive and disorganized, traits that even Belly finds troublesome at times. He reminds her vividly of Jeremiah's last-minute revelation about his spring break trip to Cabo, suggesting that it was the catalyst for their breakup, though Belly clarifies it was merely a heated argument. She then urges Steven to end his ambiguous relationship with Mia, his girlfriend, if his heart truly lies with Taylor. In response, Steven counsels Belly to share her Paris plans with Jeremiah and give him an opportunity to prove himself.
Elsewhere, Jeremiah confides in Conrad about his spat with their father, revealing a poignant longing for him that silences Conrad's intention to discuss his summer job. Meanwhile, Belly encounters Jeremiah at a lively college party and enthusiastically unveils her Paris adventure. He, filled with excitement, persuades her to embrace the journey.
Conrad and Agnes share a drink, during which Agnes confesses her past attraction to Conrad, who was then uninterested in a commitment. Their conversation drifts to Belly, prompting Conrad to admit he can no longer bear being alone with her. He abruptly departs the bar, leaving a voicemail for Jeremiah about his job and his absence from the dedication ceremony.
Back at the boisterous frat party, Belly overhears Lacie, a girl boasting about her fling with Jeremiah during his Cabo escapade. Devastated, Belly confronts Jeremiah, who reluctantly confirms the encounter but insists it meant nothing since they were separated. Belly, however, declares that she can no longer trust him and storms off, her heart heavy with disappointment.
