Sheldon and Wolowitz plan birthday celebrations for Amy and Halley, respectively. Also, Leonard receives a Christmas letter from his brother that causes him to spiral out about his own lack of accomplishments.

Kevin Hart (Jumanji: Welcome to the Jungle (2017), Saturday Night Live: Kevin Hart/Foo Fighters (2017)); Hailee Steinfeld (Pitch Perfect 3 (2017)). Also: Steinfeld and Alesso perform with Andrew Watt.

The chefs battle each other in a fierce Mise En Place relay; chef Alex Seidel invites the group to his farm to learn about his take on farm-to-table cuisine; the chefs are tasked with creating a meal incorporating a mystery ingredient from the farm.

A mystery unravels when an organization fighting to find a cure for vampirism enlists the help of someone in the group; old loyalties are put to the test with deadly results.