Amy's parents and Sheldon's family arrive for the wedding.

The Mandalorian and the Child continue their journey through a dangerous galaxy.

After a Jewish accountant helps him get back some money he was conned out of by Jim Kaplan, Peter attempts to convert Chris to Judaism to help him perform better at school.

The Replicator zeroes in on the BAU when the killer targets one of the team as the next victim. Also, the BAU is called in to investigate a string of deaths in Manhattan.

When Mark Mardon AKA The Weather Wizard returns to break Leonard Snart AKA Captain Cold and James Jesse AKA The Trickster out of Iron Heights, Barry must stop these rogues from taking over Central City during Christmas. Meanwhile, Joe and Iris meet Wally West.

A copycat killer who goes by the name “The Trickster” (guest star Devon Graye) starts setting off bombs in Central City. In order to stop the villain, Barry and Joe meet with the original Trickster, a criminal mastermind named James Jesse (guest star Mark Hamill), who has been imprisoned for 20 years. Things quickly go from bad to worse when the Tricksters unite and take Henry prisoner. Meanwhile, Iris asks Eddie for help with a case, and flashbacks show how Harrison Wells came up with the idea for the particle accelerator.

With Alchemy and Savitar still looming threats, Barry is unable to focus on the Christmas holiday and his relationship with Iris.

A family dinner is interrupted by galactic space thief Gadfly Garnett. Miles needs to follow quickly in his dad's footsteps as a DIY expert to save Loretta.

When Luke Skywalker, C-3PO and R2-D2 burst through a wall backstage in search of Chewbacca, The Muppets promptly welcome Mark Hamill as the show's guest star. 'The Force' is with The Muppets as they play heroes from a galaxy far, far away.