After failing a military training mission, the team members are determined to prove themselves when an Internet infrastructure is threatened by a bomber.

When Sylvester accidentally triggers an explosive device during an investigation, Team Scorpion must focus on finding who's responsible even while their friend's life hangs in the balance.

When Team Scorpion travels to Ireland for Megan’s one-year memorial, Walter discovers that a nearby lake’s natural disaster has created a poisonous cloud that could kill everyone in the village. Also, Cabe and Toby try to alleviate the tension between Tim and Walter.