There is a cab (always numbered seven) that appears when it should not. It does not belong to any company. Its driver changes, or seems to. The cab arrives at moments of crisis, transition, or desperate need, and its passengers do not arrive where they expected.
Cab Seven is a frequently reported mechanism of involuntary transit to Nod.
The Pattern
The accounts are remarkably consistent across decades and geography. A person in distress, fleeing danger, lost, abandoned, or in the grip of anguish or fear so absolute that rational thought has collapsed, encounters a taxi where none should be. The driver knows their name, or seems to know more than a stranger should. The ride is unremarkable until it isn't. A turn onto an unfamiliar road. A bridge that was not there before. The city outside the windows changing in ways the passenger cannot quite articulate until they step out and realize they are no longer in the world they left.
The cab is always number seven. The passengers never asked to go where they ended up. The driver, when sought after the fact, is never found.
Who Comes
Cab Seven does not select randomly, though the criteria are opaque. The passengers share certain qualities: they are often young, often in danger, often possessed of latent abilities they have not yet discovered. Some are brought to Nod because the city needs them. Some because Earth no longer has a place for them. Some, it seems, because something about them caught the attention of whatever intelligence operates the cab.
The Question
No one knows who operates Cab Seven. The leading theories range from the mundane (a network of Scribes running a recruitment operation) to the theological (Nemo personally drawing useful individuals to the city) to the unsettling (the cab is an autonomous phenomenon, a recurring glitch in the Veil that has developed something like intention). The questions of who runs it and why have not been answered and the cab does not pick up the people who would like to ask them.