痴迷练拳的唐龙（李小龙 饰）不远万里来到罗马帮助深陷麻烦的陈清华（苗可秀 饰），因某大老板（Jon T. Benn 饰）看中了清华饭店的地皮，为逼其就范，派流氓日夜骚扰。阿龙一分钟就撂倒了四名流氓，后又收服了饭店众伙计，打晕了埋伏在公寓的枪手（Homan Tapsell 饰），制服了大老板及其十余手下，救回了被掳走的清华。贼心不死的大老板从美国请来空手道高手Colt（Chuck Norris 饰），并将阿龙诱骗至斗兽场……Tang Lung arrives in Rome to help his cousins in the restaurant business. They are being pressured to sell their property to the syndicate, who will stop at nothing to get what they want. When Tang arrives he poses a new threat to the syndicate, and they are unable to defeat him. The syndicate boss hires the best Japanese and European martial artists to fight Tang, but he easily finishes them off. The American martial artist Colt is hired and has a showdown with Tang in Rome's famous Colosseum.