When the girls go to prison to see Caroline’s father, Martin, perform in a musical, they tell him their plan to use Caroline’s movie money to convert their cupcake window into a dessert bar.
Rip tells the team they are headed to the future to take out a powerful ally that Savage needs in order to conquer the world. However, when Rip reveals the ally is a 14 year-old boy who will one day grow into an evil dictator, the team is split about the morality of killing a child, even if it does save the world. Meanwhile, Sara talks Snart through a rough patch and Ray learns something that could impact his future with Kendra.
Meredith goes on an ambulance ride with Owen and Nathan to pick up a heart for a transplant patient. Musician & MS patient Kyle Diaz is admitted to Grey Sloan Memorial with a tremor in his hand, and the residents apply for the Preminger Grant. Meanwhile, Catherine continues to insert herself into Jackson and April's business against Richard's wishes.
The election is in full swing, which means everyone is doing their best to take down their opponents, but when a potential leak threatens several candidates, they have to work together to keep their secrets safe. Boundaries are pushed and lines are crossed as we find out just how far some people are willing to go to protect themselves.
Jaha employs a terrifying new method to convince Abby to join his cause, Kane is on a mission. Bellamy is hit with a hard truth. Monty finds himself in a precarious situation. Jasper rushes to save one of his own.
Secrets are revealed when Amy and Sheldon join Penny and Leonard on a weekend cabin trip. Raj is more excited about Howard's and Bernadette's impending parenthood than they are.
After Red learns that a tactical nuclear weapon is being targeted by thieves, it's a race against the clock as the task force struggles to stop them -- and prevent an imminent nuclear disaster. Meanwhile, Tom and Liz make a decision that will change their relationship forever.
A former student leaves a threatening letter for the gang, and they quickly realize they're stuck in the middle of his sick, murderous game. Trapped in school at night, with corpses piling up, the teachers fight for survival.
Defeat for the Vikings calls Ragnar's leadership into question as they evacuate their camp and move back down river. Ragnar remains inscrutable until he orders the fleet to beach at a cliff face and unveils an ingenious plan. Rollo and Gisla have news that strengthens Rollo's position at the French Court whilst Count Odo fails to identify his true enemies, with fatal consequences.