Adam Mongrain had quite the shock two weeks ago when he walked into his Montreal apartment at 2 a.m. to find a dozen strangers having a party there.

His home had been ransacked and smelled of cannabis and cigarette smoke. People had even been cooking his food. The tenant suspects the unwelcome visitors were connected with travel website, Booking.com.

“I immediately felt like dreaming. Nothing was familiar because everything was torn apart,” Mongrain told CTV Montreal. “There are pictures but it's hard to convey at the extent which things were trashed.”

Mongrain confronted them, asking them who they were and what they were doing in his house.

“And they say, ‘I'm here with Booking.com.’ And I say, ‘You can't be, I'm not on Booking.com,’” he recounted. “This is my place.”

The landlord had recently put the downstairs apartment on the short-term rental website, so Mongrain believes the renters just walked into the wrong unit.

It was only after the uninvited partygoers had left that he noticed how many of his possessions were missing.

“They took the passports. They took all the cash we had. They took cash from my wife's daughter that she had saved up from babysitting for Christmas presents,” Mongrain said.

He says estimates that $6,000 worth of his possessions were missing or stolen. Making things worse, he said he had to pay a professional cleaner $3,500 to fix the place up.

In a statement to CTV Montreal, Booking.com said: “In the very rare instance that a customer engages in unlawful behaviour, we encourage our partners to reach out to local authorities.”

Mongrain filed a police report but mentioned that the partygoers hadn’t forced their way into his home.

Montreal police said they are investigating.

Housing lawyer Ted Wright with the Westmount Legal Clinic said the legal obligation lies with the landlord.

“The landlord has an obligation to give safety and security and if anything compromises that because of the landlord's actions, then the landlord is liable and the tenants can sue,” he told CTV Montreal.

Wright added that landlords need special permits to rent out their units for short-term rentals, so tenants can check city hall records to see if their building is on the market.

“If you think the landlord is even thinking about it, you send a legal letter saying ‘if you do this, this is what I'll do.’ You have to protect yourself, and you might even have to change the locks,” Wright said.

But as far as Mongrain knows, the downstairs apartment is still up for rent.

Recently, the city has cracked down on the number of short-term rental units after residents complained that the downtown core was filled with them. The main issue is that tourists who stay there can sometimes leave a mess, which residents say they end up cleaning up,