The Scorpion team races to find who used a genetically targeted virus on four children, one of whom is the daughter of the governor. This case strikes close to home for Walter and Agent Gallo.
After Team Scorpion fails a military training mission, they are determined to prove their worth to Cabe and Homeland Security when a bomber threatens to take out the internet infrastructure of the entire Southwest.
Scorpion asks a music artist for help after he creates an algorithm that can produce popular songs and may find the killer of a music blogger; Drew asks Walter to help find a way to make a connection with his son.
Sylvester is seriously injured when he accidentally triggers an explosive device during an investigation, and Team Scorpion searches for who is responsible.
A 10-year-old boy is trapped in a rockslide/sinkhole near the beach. The team must find a way to rescue him before the rising tide fills it up with water.
Team Scorpion is tasked with uncovering a mole inside the CIA whose judgment is clouded by matters of the heart and is being coerced into stealing deadly chemicals. Also, in preparation for the case, Paige gives Walter a flirting lesson.
Team Scorpion goes undercover on a cruise ship to locate and disable deadly stolen rockets. Meanwhile, as Valentine's Day approaches, Toby and Happy help Ralph, who is in the throes of his first crush.
A tech billionaire hires the team to rescue his kidnapped daughter. Meanwhile, feelings are hurt when Walter gives an interview and fails to acknowledge the other members of the team.
While on a mission to save lost hikers, Team Scorpion's helicopter crashes, igniting a massive wildfire that quickly closes in on them. Also, Sylvester must help their injured pilot who is unable to make it to safer ground.
To protect a key witness who is en route to testifying against a deadly drug cartel, Team Scorpion takes her on the run, with the cartel hot on their heels.
Walter learns Cabe's long-hidden secret regarding the Baghdad mission and it threatens to tear Team Scorpion apart. Meanwhile, Ralph puts his life in danger to help the team.
Team Scorpion is torn apart and uncertain about their future as a unit, but they are forced to come together to save Walter's life when his car teeters on the side of a cliff.