Bob and Greta De Jaegher are happily married for 40 years. They can look back on a rich and fulfilled life. Their 2 sons Steve and Carl have a successful life as well. Steve is a talented and recognized film-director and Carl is a promising cook. Steve's wife Billie wrote a bestseller about happiness and wants to start a family with her husband. Brother-in-law Rik, who works at the zoo, tries to pick up his life with his kids, after his wife died two years ago. To mark their 40th wedding anniversary, Bob and Greta organize a family weekend. They want to announce something very important. Their new plans are a sure hit for the family De Jaegher, but that's not the only thing - Wat had to be a cheerful gathering of the family, turns out to be something nobody expected.

由克里斯（Titus De Voogdt 饰）和皮特（Stef Aerts 饰）带队并由数名十几岁的男孩组成的童子军即将前往靠近法国边境的某座森林里露营，出发前他向孩子们讲述了一个可怕的传说，据说森林里有一种被称为“凯”的半人半兽怪物肆虐横行，当地人闻风丧胆。它的模样如同人狼，凡是被它咬过的人都会受到感染变成人狼。孩子们群情激昂，决心痛揍人狼，随后跟随克里斯坐上卡车出发。阳光明媚的时节，孩子们在露营地快乐玩耍，不过并不受众人待见的小男孩萨姆（Maurice Luijten 饰）似乎格外在意“凯”的存在，他在挖洞时声称一度看到“凯”的身影，随后更在营地附近发现一处神秘的巢穴。 夜幕降临，可怕的身影悄悄向营地接近，萨姆的命运发生彻底改变……