The title refers to the system that connects the entire solar system together making planetary transport occur in minutes. But the transit system is suffering from a series of unexplainable power losses that even the maintenance team, the floozies, cannot discover why they have occurred. A Lunarversity student named Kadiatu, with a mysterious heritage, needs cash and joins the floozies in the system. Benny ends up at the other end of the line.
Transit is a hard book to like.
Who novel that was quite unlike any other that had gone before it, and one that has not been matched in the years following it's publication. This is not necessarily a good thing. Transit is a very nasty, unpleasant book which frankly is not good Doctor Who, but there is something about it that makes it a good novel. This works against the character really as it isn't immediately obvious that she has been possessed, and so she becomes unlikeable, and rather than cement her relationship with the Doctor, most of this novel seems to distance them. It's a testament to the strength of the character, and the subsequent use of her in later books, that she's survived as long as she has, as it would be correct to say that on the basis of this novel, she wouldn't have lasted very long at all.