Private Boat

In a private terminal at the Port of Boston there is a houseboat. This houseboat has been anchored there, permanently, for at least 50 years. The eccentric owner has maintained all fees and taxes and is in good standing with the Port Authority.
Still, even if the owner wasn't finacially responsible, no one would ask them to depart. Despite the owner's friendly, hospitable, if odd nature, there is a persistent air of unease around the boat and the area of the Port surrounding.
Very few people have taken the owner up on offers of hospitality, but those who do recount a wholly unbelievable tale:
When you step into the houseboat, it's as if you're sent backwards 50 years in time. Looking out windows depicts a cityscape of antiquity and the television recieves live broadcasts of programs of the era (including news programs). If you look out the open door, you see the city as it stands today. When the door closes, you can see the 50 year old skyline through the port opening.
Some visitors who spend time with the owner notice something particularly disturbing: an almost uncanny resemblance to their host, despite obvious age differences. Though this is odd, the owner is friendly and trustworthy (ignoring the air of unease most feel), so it isn't surprisng if casual friendships build between a guest and the proprietor.
All this would, of course, be very strange and worthy of note, but dismissed as some form of elaborate hoax or illusion, if it weren't for one additional detail.
Whenever someone elects to spend the night in this houseboat after an evening of conversation and a few drinks, they are never heard from again.
When the guest awakens in the morning, the owner is nowhere to be found and suddenly, the city skyline never changes back to its contemporary appearance when exiting the boat.
Under the bed there is a briefcase full of $100 bills with a letter stapled to a list.
The letter simply reads, "You have 50 years to follow these instructions if you wish to free yourself from this hell.
The clock is ticking. Get to work."