Seth and Ryan join Caleb in Las Vegas for his last days as a bachelor; Kirsten plans a bachelorette party for Julie; Marissa learns something about Teresa.
When Walter is accidentally launched into space in a rocket, he hallucinates about Paige as his oxygen runs low, and Team Scorpion works feverishly to find a way to bring him home before he suffocates.
The truth behind Fitz’s turn is revealed, and it could bring down all of S.H.I.E.L.D.
After a group of wealthy women are robbed at a luxury day spa, evidence leads the the CSIs to believe that this is a part of a much larger car chopping scam and each of these women are being targeted for a home robbery. Matters become worse when Horatio discovers that Marisol was also at the spa during robbery and he must now protect her when her life is threatened. Meanwhile, Ryan must deal with the fallout after he freezes during a shootout.
Supergirl gains a new ally when the lightning-fast super hero The Flash (guest star Grant Gustin) suddenly crosses over from an alternate universe and offers to help Kara battle Silver Banshee (aka Siobhan) and Livewire in exchange for her help in finding a way to return him home.
