The Big Boss (1971)

Cheng (Lee), a young Chinese man sworn to an oath of non-violence, is sent to live in Thailand with his uncle and cousins. His promise to his mother not to fight is repeatedly tested when he goes to work in the local icehouse for an abusive overseer. When some of his cousins are killed, after discovering the icehouse is actually a front for a heroin-smuggling operation, Cheng sets out to exact revenge.