SDU: Sex Duties Unit

The Special Duties Unit (SDU), nicknamed Flying Tigers, is the first paramilitary tactical unit of the Hong Kong Police Force to be specialised in tackling serious crimes. Since its establishment in the 1970s, the SDU has been consistently recognized as one of the top three tactical units in the world.

It is an annual custom that several members of the SDU are chosen to take part in military training programmes from around the world. The chance to work with the Navy SEALs in the United States this year is handed by Inspector Michael to Team A, which is known for its teamwork, at the expense of Team B, whose members have failed to finish a 10km run in 35 minutes. The decision has incurred the wrath of Team B's second-in-command, Keung, who is also unhappy about his own failure to make captain over the years. It only gets worse when Michael reveals to Keung that his team member Josh has been applying for a transfer to Team A.