Barbara is a very rich girl who falls in love with Norman Phiffier, a poor young man. She doesn't tell him who she really is and prepares to marry him. But, Mrs. Tuttle (Barbara's mother) doesn't want her daughter to mary such a poor man. So, she hires Norman at one of her big stores, and gives him the most difficult and disgusting works. She hopes that seeing Norman humiliated, Barbara will finally leave him. But things don't work exactly this way...

二十年前，金哥的母亲死在逃荒路上。临死时，她将怀里的儿子交给丈夫，拼着最后一口气说：“快抱着孩子去吧，找路，只有向前。” 二十年后，金哥长大，他与沉默刚毅的老张，率直憨厚的章大，千灵百怪的韩小六子，年轻有为的小罗，聪明而有学问的郑君等五个青年朋友,不甘在城市里受欺侮剥削，同到内地筑路工程队，参加修筑一条重要的军用公路。公路修筑到一处险要地段，金哥等人就 在村口丁福记饭铺包饭，与饭铺丁老板之女丁香和投靠丁老板的江湖女艺人茉莉结下友谊。军事形势日趋紧张 ，筑路工人和士兵昼夜不停，合力施工。敌人鉴于这条公路对侵略政策不利，暗中指使汉奸进行破坏。汉奸邀请金哥等六工人赴宴，席间，以谎言 笼络不成，用金钱收买，又不成，遂 囚六人于地下室。丁香和茉莉因金哥 等久去不回，怀疑出事，翌日以替汉奸烧菜为名，进入汉奸住宅，用计救出金哥等人。老张因掩护同伴脱险， 在与爪牙搏斗时牺牲。 金哥回村后，当地驻军闻报，及时惩治了这伙汉奸。公路修通后，敌机突然来袭。金哥等人奋起保护公路，与敌机进行斗争，最后与茉莉一起壮烈牺牲。前方战事又起，后援部队从新修公路开赴前线。这时，唯一幸存下来的丁香，目送飞驶而去的军车，仿佛看到金哥等六青年仍在合力拉着铁滚前进，天空中也隐约响起筑路工人的《大路歌》声。