The nine remaining home cooks return to the MasterChef kitchen, where judges Gordon Ramsay, Graham Elliot, and Joe Bastianich give them their next Mystery Box Challenge. During this challenge, the contestants' every move will be watched, and their work in progress will be sampled. When time is up, three dishes will be tasted, and the cook with the best dish will get a huge advantage in the next Elimination Challenge.
When they lift their boxes, the competitors discover that they will each cook sea urchin - complete with poisonous spines. Chef Ramsay then gives them a quick lesson on how to cut open the animal to remove the uni cut.
The cooks are then given access to a limited pantry of ingredients. They will have 60 minutes to prepare their dishes. Chef Ramsay calls Tali "one brave man" when he learns that Tali plans to present an uni shooter with a hint of tequila. Felix intends to mix Japanese and Italian influences by preparing a risotto. And Stacey opts to make a California roll.
Having carefully tasted everything throughout the challenge, the judges take one final look to identify three standout dishes. Their first pick is Felix's. She has created an uni and pea risotto with ginger, pearl onions, and sake. Chef Ramsay calls her entrée "breathtaking." Graham says that it's a complex, technique-driven dish. Joe declares that Felix is back in the competition.
Josh is the second home cook to make it into the top three, with a dish that looks like it was plated to come out of a restaurant. His handmade noodles with rock shrimp and uni cream sauce lands him a spot before the judges for the first time. Although Josh doesn't know the name of the type of pasta he has prepared, it happens to be the same kind that Joe uses when he prepares uni in his own restaurant. Josh's dish is a hit with the judges. The final competitor on top is Stacey, who presents shrimp sushi with uni aioli. Gordon says it's "beautiful" and calls Stacey a dark horse in the competition.
The victor, who will have a huge advantage in the upcoming Elimination Challenge, is Felix. The judges take her into the MasterChef pantry and tell her that it's time to go fishing. They present Felix with a table filled with the pick of the ocean: nine delicious fish, including fresh water and salt water varieties. She gets to choose the one that she wants to prepare and assign one to each of her competitors.
While she knows that the easiest fish to prepare would be the salmon, she chooses the halibut. Feeling that her biggest competition is Becky, Felix gives her the difficult-to-filet rockfish. Frank is next on her hit list, and she assigns him the catfish because she believes that he's never cooked it before. Then she chooses the spiny John Dory for Monti, whom she hopes to knock out of the competition. She gives the arctic char to Tali, the coveted yellowtail to David, and the easy-to-prepare salmon to Christine.
A beaming Felix returns to her station, while the other chefs learn about their fish of the day. After five minutes of shopping in the pantry, the cooks now have 60 minutes to prepare an amazing fish entrée. At the end of the challenge one or more competitors will be eliminated, so it's time to sink or swim.
The judges say that Felix has seized her advantage to send Becky, Frank, or Monti home. Even though Tali has been given a dream ingredient, arctic char, he shocks Chef Ramsay when he tells him he'll be sous-viding the oily fish.
Christine's panko-crusted salmon seems pedestrian to Joe, and the judges worry that she's panicking a bit. Although Monti was the target of Felix's competitive strategy, she has filleted her fish perfectly. But with just three minutes to go, Tali's sous-vide arctic char is still stone-cold.
The judges start their review with Felix's poached halibut with bamboo rice, asparagus, and lemon applesauce. They determine that she has blown her advantage by choosing a difficult fish, which she then overcooked.
Next up is Monti. The judges say that she rose to the challenge by preparing a perfectly cooked filet of John Dory, accompanied by baby asparagus and roasted almond sauce. Chef Ramsay remarks that Felix's plan to take out her biggest competition in the challenge has backfired.
Next, Frank serves his fried catfish with eggplant-and-coconut leek sauce. Felix's second attempt to weed out the competition is shot down when Graham tells Frank that he loves the flavors of the dish. Felix's final effort to take down the strong competitors also fails when Becky's pan-fried rockfish filet with celery root puree and Chardonnay sauce is a success.
Despite having an easy fish with which to work, David is told that his yellowtail with aioli potatoes and red cabbage coleslaw is raw and overly complicated. Meanwhile, Tali's sous-vide arctic char over green lentils is a complete failure according to Joe, who chastises him and says that he has consistently disappointed the judges.
Christine is the final cook to present her dish. She brings forward a baked salmon in panko breadcrumbs with rice and stir-fried vegetables. The fish is overcooked and visually unappealing to the judges. Even though Felix tried to help Christine by giving her the easiest fish, it didn't pan out.
The judges now choose the cooks who presented the two best dishes: Monti and Frank. They will be team captains in the next challenge. They pick David, Tali, and Christine for the bottom three. In the end, Tali is sent home.