A tombstone that slid open to expose a secret compartment was found to contain opium, according to the RCMP in B.C. A tombstone that slid open to expose a secret compartment was found to contain opium, according to the RCMP in B.C. (RCMP)

Four people in Metro Vancouver are in grave trouble with the law after an imported tombstone was found packed with what police call an unprecedented amount of opium.

The 550-kilogram stone was shipped to B.C. from Iran and inspected at Vancouver International Airport, where border agents discovered a hidden cavity containing 56.8 kilograms of opium.

It was the biggest opium seizure ever made in the province, police said.

The tombstone was then delivered to its intended address in the Vancouver suburb of Coquitlam, which police raided the next day, leading to the arrest of a 39-year-old woman and her 48-year-old husband.

A 51-year-old man who had been renting space at the address was later arrested in North Vancouver, along with his 55-year-old brother.

The RCMP said it's recommending all four be charged with importing a controlled substance and possession for the purpose of trafficking.