In the Season 3 finale, three weeks after crash landing on a deserted island, tensions run high for the team when they must battle to overcome their relationship obstacles with each other in order to be rescued.
The team's electronics-free getaway in the mountains on Christmas Eve takes a dangerous turn when they encounter a group of gunrunners who kidnap Ralph. Meanwhile, Tim makes an important decision about his role with Team Scorpion.
Walter's forced to swim through the deadly La Brea Tar Pits in order to save a woman who's trapped in the tar before she runs out of oxygen. Elsewhere, Veronica helps Ralph with his troop's cookie sale, unbeknownst to Paige.
The team travel to Ireland to attend Megan's memorial, but Walter discovers a natural disaster in a nearby lake created a poisonous cloud that's threatening the entire village. Meanwhile, Cabe and Toby try to alleviate tension between Tim and Walter.
The team ventures into a vast cave system to prevent a bat population from destroying the North American ecosystem before Halloween. Then, the team helps stage pictures of Halloweens from Walter's past for his upcoming immigration inspection.