Free and breezy Astrid Bell lives in the moment, working as a bike courier in busy London, placing down no permanent roots or committing herself to relationships that might not make the distance. She shares a crumbling old house in an established street with a bunch of other displaced young people who have little in common other than the fact that money is short and they all agree that the location is good. One night Astrid is accidentally knocked off her bike by an elderly neighbour - no big deal really other than a few cuts and scrapes, but it is what happens after that disturbs the life of the otherwise quiet street. Peggy Farrell the next morning is found dead amongst the dustbins, clearly by the hand of another, and Astrid and her friends were the last to see the poor woman alive.
Attracting trouble once again, Astrid is called to collect a parcel from a wealthy woman's home and finds no parcel, only a dead woman. As she is questioned by the police it isn't immediately obvious to her what the connections to the two deaths are, bearing in mind that is was pure co-incidence that Astrid was the courier called upon that day. The police however are firm and insist that the common factor in this murder, and in subsequent others, of course, is Astrid herself.