In Istanbul, you lead a group of one merchant and four assistants through 16 locations in the bazaar. At each such location, you can carry out a specific action. The challenge, though, is that to take an action, you must move your merchant and an assistant there, then leave the assistant behind (to handle all the details while you focus on larger matters).
If you want to use that assistant again later, your merchant must return to that location to pick him up. Thus, you must plan ahead carefully to avoid being left with no assistants and thus unable to do anything…