A solar storm knocks out power in Los Angeles, and Team Scorpion must help a teen pilot and his girlfriend who are lost over the Pacific without navigation or radio contact. Also, during the crisis, Walter must look after a group of Ralph’s classmates, and Cabe tries to tell Allie finally that he loves her.

Team Scorpion must work with Toby’s nemesis, Quincy Berkstead, and his wife, Amy, Toby’s ex-fiancée, when they are locked inside an artificially intelligent doomsday bunker that aims to kill them. Also, Walter is distracted by his recent dream where he is married to Florence, not Paige.

On Christmas Eve, when Walter chooses work over spending quality time with his friends, he falls down the stairs and hits his head, and as he lays unconscious, he enters a dream world where Team Scorpion never existed.

As Team Scorpion anxiously awaits the verdict of Cabe’s trial which could send him to prison, they focus their nervous energy on trying to save a dog stuck in a cistern.

As Cabe’s trial looms over Team Scorpion, a simple case goes sideways when they help a father and his daughter whose plane crashes nearby. Also, Paige helps Walter navigate his feelings about Cabe’s possible future in prison.

On Thanksgiving, Team Scorpion's new neighbor, Florence, joins them at sea on a mission to destroy a floating island of trash, but her flawed contribution leaves her, Walter and Happy stranded on the quickly dissolving island. Also, Toby works with Cabe to uncover the details of his father's death that he has suppressed since he was a boy.

For Sylvester’s birthday, Team Scorpion visits a renaissance festival, but the revelry is cut short when a group tries to rob a nearby police evidence locker. Also, Paige grows weary of Walter’s play-by-play of all the historical inaccuracies at the festival

While tracking a device that can prevent a nuclear meltdown through the Los Angeles sewers, Walter learns the nuances of listening and not offering advice to Paige. Also, Team Scorpion meets Florence, their new neighbor at the garage, after she sends a mix of smelly chemicals through their shared ventilation as a warning to keep the noise down.

At Halloween, Team Scorpion takes on a case to prove the existence of ghosts on the Queen Mary but find an all-too-real disaster when they locate a “ghost ship” on a deadly collision course. Also, Walter considers taking note of Paige’s interests to benefit their relationship.

While attending a tech convention, Team Scorpion is taken hostage by a group attempting a virtual heist.

While decommissioning an old nuclear missile, a simple accident causes Team Scorpion to endure exposure to toxic vapor while trying to prevent the nuke from detonating. Also, Paige confronts Happy about constantly tagging along with her and Walter.

When poachers almost kill a pregnant endangered deer, Team Scorpion recreates the animal’s womb to try to save it and its baby’s life. Also, Happy and Toby discuss the future of their family.

Team Scorpion continues to work with their nemesis, Mark Collins, in order to prevent an extinction event that could end humanity. Also, Cabe’s last-minute decision while on the case leads to the possible end of his career.

Team Scorpion must work with their old nemesis Mark Collins in order to prevent the extinction of mankind. Also, Walter and Paige awkwardly navigate their new relationship.