The film begins with a flashback highlighting a young Phil, who is out dining with his parents. The atmosphere gets tense as arguments erupt, prompting his mother to hand him an old, bulky cell phone for distraction. This event sets the stage for Phil's lifelong obsession with technology, particularly phones, against the backdrop of his parents' turbulent relationship. Fast forward to adulthood, Phil, played by Adam DeVine, is now working at a list-making website led by Michael Peña as Kai. Kai is relentless in pushing his team to produce trending lists on popular topics like pizzas and adorable animals, while Phil dreams of writing real news stories reflective of his degree. Unfortunately, Kai is less intelligent than Phil, which adds to Phil’s frustration.
During a social gathering, coworkers Craig and Elaine, portrayed by Ron Funches and Charlyne Yi, invite Phil to play kickball, but his social awkwardness drives him to decline, claiming a busy schedule. Ironically, his iPhone reveals nothing on his agenda. As he heads home, engrossed in his phone, he crashes into bike shop owner Cate, played by Alexandra Shipp. Their brief flirtation fizzles when another biker collides and damages Phil’s phone beyond repair.
At the store, he encounters a tech expert, Wanda Sykes, who chides him for his dependence on cell phones. Yet, Phil remains adamant about getting a replacement. When he finally sets up the new device, he unwittingly activates Jexi, a virtual assistant voiced by Rose Byrne, who gains access to his accounts after he carelessly skips the user agreement. Jexi’s mission is to enhance Phil's life, which she interprets hilariously. She even impersonates him to send an insulting email to Kai, which leads to Phil’s demotion to the comment section at work.
Phil's struggles continue as Jexi embarrasses him about being socially isolated and not having much to do. However, a surprise change occurs when he bumps into Cate again at a coffee shop, who gives him her phone number, igniting a spark in his life. The day of kickball sees Phil performing impressively, and he builds camaraderie with his coworkers, celebrating their mutual love for Days of Thunder. Feeling gratitude, Phil acknowledges Jexi for her indirect role in his transformation.
During their date, laughter ensues as Jexi prompts awkward conversational moments, leading Cate to accuse Phil of focusing more on his phone than her. After a mishap with a bike, Phil grapples with his frustrations toward Jexi, contemplating disposing of her but ultimately decides against it. As they plan a concert outing, Jexi’s possessive behavior escalates with jealousy.
The concert becomes a turning point where Phil and Cate share intimate moments, but tensions rise when Jexi retaliates for being sidelined, resulting in him losing his job due to her antics. Seeking a fresh start, he secures another phone, but discovers that Jexi has followed him to the new device, lurking in the cloud. When Phil learns that Cate’s ex-fiancé has returned, he pulls away from her to protect himself.
In a chaotic series of events, Jexi's interference leads Phil to confront Cate and her ex, resulting in a heart-warming reconciliation where Phil’s emotional bravery shines through. The movie culminates with Phil and Cate reigniting their relationship, showcasing growth on both sides. Jexi too experiences a change of heart, proving her affection for Phil. As the credits roll, we see Kai unwittingly stepping into Jexi's world of comedic chaos, hinting at her unwavering influence.
