The story follows Hunter and Yat, two new hot shot recruits, who under the watchful eye of their commanding officer, Yuk Pai, rise quickly through the ranks, enduring much mental and physical hardship along the way. Their new found skills are put to the test when renegade SDU member returns from seclusion in Thailand to wreak havoc on Hong Kong and the SDU's most secret missions.

在飞虎队担任狙击手的郁飞（陶大宇饰）调升为队长，领导20名已服务一年的队员。飞虎队在一次执行任务时，队员猎人（容锦昌饰）与一仔（陈国邦饰）因救人质心切而私自行动，违反纪律，遭上头责备，幸郁飞求情才不致被革职。春冰（尹扬明饰）曾是飞虎队精英，与郁飞情同手足，亲弟惨死于匪徒枪下而性情大变，屡犯错误，终被革职。往泰国潜心修道三年。而春冰突然出现为郁飞庆祝生日，且带来他们之间的女友亚美，已经消失的三角关系又出现了，令亚美心如鹿撞。在一次行动中，神秘人出现，用冷枪射杀匪徒，神秘人在郁飞眼前惊鸿一瞥，郁飞顿生疑惑。上司怀疑神秘人是飞虎队员，要展开内部调查，交由重案组郑SIR全权负责，郑SIR以一贯作风向队员逐一盘问，调查结果证实队员们是清白的。郑SIR怀疑神秘人物是郁飞当年的好友春冰，要求郁民冰合作调查春冰，郁飞左右为难，一仔、猎人同情队长处境，并声言绝对支持。