Every spring, two million partygoers flock to Cancun for a week or two of pure hedonism - the Mexican resort is second only to Ibiza in the party stakes for young Brits. But as Stacey Dooley discovers, behind this famous spring break hotspot there's a darker side to Cancun that the tourists rarely get to see. Stacey joins the police to see the daily struggle they face to protect the tourists and mop up the trouble they cause. She also spends time with the medics responsible for dealing with the casualties when things go wrong. Investigating what's hiding behind the glossy resorts and brightly lit megaclubs, Stacey finds out why Mexico's military marines and armed police patrol them, and reveals what life is really like for the thousands of Mexican hotel workers who cater to the holidaymakers.

• Stacey Dooley