Dex goes undercover after she is hired by a local politician to dig up dirt on his political opponent. Meanwhile, Grey and Liz’s romance continues, and Dex celebrates a tense…

Team Scorpion must prevent an incoming tsunami from hitting a vulnerable nuclear power facility, and Toby secretly helps his ex-fiancée retrieve her stolen identity.

The gang fudge history by claiming that Paddy’s Pub was responsible for cracking the Liberty Bell in an attempt to turn their dive into a Philadelphia landmark.

Barney freaks out when Marshall bequeaths a “slap bet” slap to Ted and Robin. Meanwhile, Lily’s estranged father shows up for Thanksgiving.