‘The Swarm’ Episode 4 Preview: Plot, Cast and Exclusive Clip

The CW’s dramatic thriller The Swarm continues season one with episode four, “The Mystery.” Directed by Barbara Eder from a script by Steven Lally, Marissa Lestrade, Chris Lunt, and Michael A. Walker, this exclusive clip shows a South African town under attack by crabs marching out of the sea.

Episode four airs on October 3, 2023. New season one episodes arrive on Tuesdays at 9pm ET/PT.

The ecological thriller is based on Frank Schätzing’s bestselling novel and stars Alexander Karim as Dr. Sigur Johanson, Cécile de France as Dr. Cécile Roche, and Krista Kosonen as Tina Lund. The ensemble also includes Leonie Benesch as Charlie Wagner, Joshua Odjick as Leon Anawak, Takehiro Hira as Riku Sato, and Rosabell Laurenti Sellers as Alicia Delaware.

Barbara Sukowa is Professor Katharina Lehmann, Oliver Masucci is Jasper Alban, Klaas Heufer-Umlauf is Luther Roscowitz, Lydia Wilson is Sara Thompson, Eidin Jalali is Rahim Amir, Takuya Kimura as Aito Mifune, and Sharon Duncan-Brewster is Samantha Crowe.

“The Mystery” Plot: Dr. Roche (de France) informs a commission about the dramatic situation on the French Atlantic coast. Meanwhile, Sigur (Karim) and Tina (Kosonen) are back on board the Thorvaldson to survey the seabed again for ice worms and find the worms have continued to spread dramatically.

The Season 1 Plot, Courtesy of The CW:

Around the world, strange happenings, borne out of the oceans: Whales destroy boats, deep sea crabs attack beaches, mussels block container ships. An unknown ice worm destabilizes continental slopes and triggers tsunamis. A deadly pathogen spreads into the drinking water. Across the globe, lives are increasingly imperiled, the situation worsening by the day — and yet, nobody can draw a connection between the seemingly random attacks. Except for a group of scientists who come together through their shared sense that something bigger is at play: an intelligent life force, dwelling in the deep — capable of manipulating the ocean, and everything that resides in it.

A being which has borne witness to our destruction of the seas and has decided to drive us to extinction. But hardly anyone believes their findings. And so, the group is forced to undertake a life-threatening mission, tracking the intelligent life force within the Arctic Ocean. It is a mission they know may claim their lives.