Tamna the Island is set in 17th-century Joseon times as a young English castaway, William Spencer(Pierre Deporte), comes to the island and meets Jang Beo Jin (Seo Woo), Park Kyu (Im Joo-hwan), and Yan Kawamura (Lee Sun-ho). The name “Tamna” refers to what is now called Jeju.
In Episode 4, Yan urges William to escape the island. Beo Jin, who goes out searching for him at night gets arrested for hiding thieves.
In Episode 5, Beo Jin faints under water and Kyu is furious with William for trying to take 'advantage' of her. When Beo Jin regains consciousness, she makes Kyu a nice meal after finding out he saved her life.