Having proved that his social ineptness is dangerous beyond belief, the Wolf Pack's perpetual fourth wheel, off-his-meds Alan, is on his way to get treatment at a rehabilitation facility in Arizona. Along with Phil, Stu, and Doug, the mismatched quartet hits the road, when suddenly, they're kidnapped by the menacing crime boss, Marshall, for reasons that date back to The Hangover (2009), and the boys' first visit in Las Vegas. But, it's been only two years since the Thai mayhem in The Hangover Part II (2011), and now, the best friends have three short days to find the whereabouts of the conniving thief, Mr Chow, and a mountain of stolen gold bullion worth millions of dollars. This time, everything ends where it all began. Will the accident-prone Wolf Pack make the same mistakes twice, and live to tell the tale?