A Montreal couple returned home after a recent evening out to discover their apartment filled with strangers having a party — drinking their alcohol, eating their food and trashing their place.

The couple's apartment, not far from the Jarry Metro station in the Villeray-Saint-Michel-Parc-Extension borough, had also been thoroughly rummaged through and thousands of dollars in valuables were stolen.

"When I stepped in, there were about 12 people partying in my place. Total strangers. Nobody who I had ever seen before," Adam Mongrain told CBC Montreal's Daybreak.

"It was completely surreal to step into my home and find people I don't know there. I didn't know what to do."

He asked the first person he locked eyes with for an explanation. Mongrain was told the group had reserved the apartment through Booking.com, a website that allows users to find deals on hotels and short-term rentals.

While an apartment on the building's lower level is available for short-term rental and managed by the landlord, Mongrain's is not. He explained this to the unwanted guests and told them to leave.

They didn't argue or question the order to get out. They simply gathered their coats and began leaving in an unhurried, orderly fashion, he said.

'We keep finding things that are missing,' Mongrain said, estimating the total taken to be worth about $6,000. (Submitted by Adam Mongrain)

Now two weeks later, Mongrain and his wife are still trying to understand what happened. ​He doesn't know how the strangers got into his place and is worried it could happen again.

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CBC Montreal spoke with his landlord. She confirmed details of his story, but said she never provided a key to Mongrain's apartment to the Booking.com clients.

The landlord declined an on-air interview.

Listen to Adam Mongrain tell his story:

Coming home to unwelcome party

Mongrain said he and his wife returned home around 2 a.m. on Nov. 10 when they found their apartment filled not just with people, but with marijuana and tobacco smoke in a usually smoke-free home.

There was also the smell of cooking food in the air as a man was busy at the stove.

"It's been two weeks and it still doesn't make sense whenever I think about it because they had ordered pizza that they didn't touch," Mongrain said. "It was still intact when we walked in and one of the men was cooking macaroni."

The people were hanging out, laughing and joking, enjoying all the snacks and alcohol they could find in Mongrain's place — all laid out on the living room table.

"It's hard to convey the extent to which the place was trashed," he said.

Laptops, babysitting money, passports stolen

In total, two laptops, two passports and jewellery were stolen, according to Mongrain, as was clothing, perfume, watches and booze.

They even stole his wife's daughter's cash — money she had saved up from presents and babysitting.

"We keep finding things that are missing," he said, estimating the total taken to be worth about $6,000.

Adam Mongrain says the strangers claimed to have rented the apartment through booking.com, but his place isn't listed. Another apartment in his building is. (Isaac Olson/CBC)

As soon as they returned home on Nov. 10, they noticed one of their laptops wasn't on the table where they had left it.

The couple asked the unwelcome guests to return the missing device as they were leaving the apartment, but it was not returned.

Feeling outnumbered, they opted to call their landlord rather than pick a fight. They asked her to forward all the information about her most recent short-term renters and then they called the police to file a report.

Montreal police aren't providing any details at this point, but they told CBC that the case is under investigation.

"Thank God we were insured," said Mongrain, noting the insurance company even helped with the cleaning — a process, he explained, that was too emotionally difficult to do himself.

The professional cleaning bill came out to $3,500 as stains on the couch and splashed soda on the walls needed to be removed. There were cigarette butts and ash everywhere, he said.

In a statement provided to CBC Montreal on Wednesday, Booking.com said it encourages people to make official complaints to police in cases where unlawful behaviour has taken place.

"We support our accommodation partners fully and will co-operate with law enforcement in all official investigations as necessary," the statement said.

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