Scorpion

Season 1 introduces Walter O'Brien (Elyes Gabel), a genius with an IQ of 197 who hacked NASA as a child. Homeland Security agent Cabe Gallo (Robert Patrick) recruits Walter and his team of brilliant misfits — Toby Curtis (Eddie Kaye Thomas), a Harvard-trained psychiatrist; Happy Quinn (Jadyn Wong), a gifted mechanical engineer; and Sylvester Dodd (Ari Stidham), a mathematician with severe anxiety and OCD — to fix a national air traffic control crisis.

The team is joined by Paige Dineen (Katharine McPhee), a waitress and single mother who becomes their "translator" to the real world, helping the socially awkward geniuses interact with everyday people. Together, they form Team Scorpion, taking on high-stakes missions involving encrypted nuclear codes, hijacked drones, biological threats, and more. Paige's young son Ralph (Riley B. Smith) is revealed to be a genius himself, connecting deeply with Walter.

The season establishes the team dynamic — Walter's emotional blindness, the growing romantic tension between Toby and Happy, Sly's phobias, and the unresolved guilt Cabe carries over a past mission where he used Walter's tech for a bombing that killed civilians.

Season 2 expands the team's scope as they face larger threats and deeper personal stakes. Walter's sister Megan (Camille Guaty), who has multiple sclerosis, becomes a central emotional anchor — Walter is desperate to find a cure. Sly falls in love with Megan and they eventually marry.

The team gains new allies, including Ray Spiewack (Kevin Weisman), a PTSD-stricken former firefighter who becomes Walter's community service buddy and later a temporary team member. Tim Armstrong (Scott Porter), a Navy SEAL and Homeland trainee, joins the orbit and begins dating Paige.

Relationships deepen — Toby and Happy officially begin their romance. The team faces betrayals from within Homeland Security, a mole in their own ranks, and a former Scorpion member turned enemy. The season's emotional climax arrives in "Arrivals and Departures," where Megan's MS takes a fatal turn. Walter is cut off from her by a hospital quarantine but reaches her in time to be at her side as she dies — devastating the entire team.

Season 3 follows the team as they process Megan's death. Walter struggles with his grief, compartmentalising until it eventually explodes. His estranged parents visit, forcing him to confront his childhood. The team rallies around him while also facing threats from a shadowy organisation that aims to weaponise their technology.

Paige's con-artist mother Veronica (Lea Thompson) arrives, stirring up old wounds. Cabe confronts his daughter's death from years past, and a romance develops between him and Allie Jones, a campaign staffer. Sly runs for city council after a personal tragedy and discovers a talent for politics.

The team faces one of their most dangerous adversaries yet — a brilliant psychopath who systematically targets each member of Scorpion. Walter and Paige's relationship grows closer, with both grappling with their feelings for each other while Paige is still with Tim.

Season 4 introduces Flo Tipton (Tina Majorino), a no-nonsense chemist whose lab is next to the team's garage. After initial friction, she becomes a valued ally and a romantic interest for Walter — causing complications when Paige finally admits her feelings for him.

Ralph grows into a teenager and takes on a more active role in missions. Sly's political campaign gains momentum. Cabe and Allie's relationship deepens. The team faces threats including a Russian weapons dealer, a killer virus, and an AI that could dismantle global infrastructure.

The season ends with the series finale "A Lie in the Sand." Team Scorpion travels to Northeast Africa to navigate a minefield during a sandstorm. But the real crisis is personal — Walter's white lie about his interactions with Flo is discovered by Paige, destroying their relationship and fracturing the team. After the mission, Sly quits, followed by Paige, Happy, and Toby.

Two weeks later, Walter runs a stripped-down "Scorpion 2.0" with Cabe and Flo. The others have formed a rival team called Centipede. The series ends on a bitter cliffhanger with Walter calling out to Paige as she shuts the door on him — their future, and the team's, completely unresolved.