In the exclusive trailer debut of Serenity, McConaughey stars as a fishing boat captain who gives tours around the peaceful Caribbean island where he lives. His quiet life gets interrupted when his ex-wife (Hathaway) returns, seeking refuge from her abusive husband (Jason Clarke) for herself and her son.

“Some of the scenes between them are the most electric I have ever been involved in,” director Steven Knight (Locke) tells PEOPLE in this week’s issue of McConaughey and Hathaway’s performances. “Matthew and Anne are two of the best actors working anywhere in the world.”

The thriller filmed on a real boat, which required the 48-year-old father of three to get his hands on some bait and tackle. “During rehearsal while Matthew was being given lessons how to fish big game by an instructor, the line he threw out was taken by a 200-lb. tuna,” Knight recalls. “He spent the next two hours reeling it in!”

The film takes a dark turn when Hathaway‘s character asks her former husband to put his talents to a different use. “My husband has never seen your face. You were right about him,” Hathaway, 35, tells him in the trailer, referring to her abusive partner. “I want you to take him out on your boat and drop him in the ocean for the sharks.”

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But shooting on the idyllic island of Mauritius in the Indian Ocean helped the cast and crew keep the mood light.

“We found a local Zydeco band who usually play weddings and they came along to the set a few times and played for us while some of us danced,” Knight, 59, says. “Also instead of trailers, we had beachfront apartments for costume and makeup. Mauritius is kind of like paradise.”

Serenity, also starring Diane Lane, hits theaters on October 19.