On Scorpion Season 4 Episode 1, the team sings about love, Waige, and how everything is absolutely genius, but the joy is quickly ruined by a phone call from Mark Collins.
He calls Walter because he had an Archimedes moment. He's been through extensive therapy, sanity has flourished. It's an extinction event. There's methane leaking out into the atmosphere. If this isn't stopped, then in 30 days half of life on Earth will be gone.
Team Scorpion needs to plug the methane fissures in seven days to prevent this extinction event, and they don't have time to do the calculations on their own to figure out where exactly the fissures are. They will have to let Mark help.
Don't worry, Cabe hooks Mark up with a stun cuff. If Mark is more than 25 feet away from Cabe, he gets one hell of a shock.
In Norway, the team works on plugging the fissures, and in typical Team Scorpion fashion, their original plan goes wrong, and they have to improvise a new solution. While working on saving the world, Mark meddles in Walter and Paige's relationship.
After their last ditch attempt to plug the fissure by setting it on fire, Team Scorpion believes they have saved the day. Unfortunately, a recent earthquake aftershock has opened dozens of new fissures, and there's even more methane spilling out into the Earth's atmosphere.