As Matthew Saunders taps into his inner hero, he courageously thwarts a purse snatcher on the subway, earning him the title of knight in shining armor to Jenny Johnson. Their romance flourishes, yet beneath the surface, Jenny's behavior deteriorates, becoming more controlling and erratic. Aggressive outbursts take a toll on Matt's emotional and physical state, leaving him in turmoil.
But this is merely the start of Jenny's metamorphosis into G-Girl, a stunning superheroine blessed with extraordinary powers—flight, super-strength, incredible speed, heightened senses, invulnerability, super breath, and heat vision—thanks to radiation exposure from a crashed meteorite during her youth. As G-Girl, Jenny's grip on reality becomes increasingly tenuous, overwhelming Matt with her demands and desires.
At the same time, Hannah Lewis, Matt's delightful coworker, secretly admires him, even while involved with a handsome yet superficial underwear model. As their friendship grows, Matt's frustration with Jenny's escalating jealousy leads him to break ties with his superhero sweetie.
In response, Jenny unleashes chaos on Matt, publicly stripping him during a pivotal meeting and ultimately costing him his architect job. This rampage culminates in Matt's public humiliation at the hands of G-Girl's wrath.
Complicating matters, Professor Bedlam, Jenny's former high school sweetheart turned villain, harbors a grudge against her for choosing others over him. He sees a golden opportunity to exact revenge and recruits Matt’s help to defeat Jenny. After some hesitation, Matt agrees, but only if the professor agrees to abandon his villainous ways.
Navigating this perilous world, Matt finds solace in Hannah, who has just ended her relationship with her unfaithful partner. Their feelings intensify, leading to a brief moment of happiness, only to be shattered when Jenny, filled with jealousy and rage, attacks them using a ferocious great white shark.
As Matt partners with Professor Bedlam to regain control over his life, he uncovers a disturbing shrine to Jenny within the professor’s lair. This unsettling discovery ignites a determination to confront her true essence.
To draw Jenny into a trap, Matt devises a romantic dinner under the guise of rekindling their relationship, hoping to lead her to another meteorite, one that will take away her superpowers. The stakes skyrocket as Hannah arrives, only to witness a fierce confrontation between her friend Jenny and Matt. Amid the chaotic struggle, Jenny's secret identity is laid bare to Hannah, while Bedlam's devious plan to drain Jenny’s powers unfolds.
In a climactic battle between Matt and Bedlam, Jenny desperately crawls towards the energized meteorite, seeking to recover her powers. Just as she reaches for it, Hannah intervenes, and the meteorite erupts with energy. Both women are violently propelled from the rooftop; however, Jenny reemerges, her powers once again at her disposal.
In an unexpected twist, Hannah also gains G-Girl's abilities, setting the stage for an alarming showdown between the two women, with Matt caught in the middle. Their destructive conflict wreaks havoc on the neighboring properties, escalating the chaos.
In the aftermath, Matt reveals Bedlam's hidden feelings for Jenny, which softens her resolve. Realizing that Bedlam is her true love, a moment of tenderness unfolds before an excited crowd.
The next morning, Matt and Hannah reconnect with their partners—now known as Barry and G-Girl—when they’re interrupted by cries for help. Jenny and Hannah, united in their newfound crime-fighting mission, swiftly respond to the emergency, leaving Matt and Barry to enjoy a long-overdue break with a beer and the ladies' previously discarded purses and clothing.
