A memorial in south London: the familiar sight of a bunch of letters, candles, flowers and postcards marking a crime scene. Young and homeless Sam (Amy Cornwell) has chosen the spot to beg – after all, people are more inclined to give generously when reminded of such horrors. Sam receives regular visits from police officer Julia (Emma Pring), whose motherly instincts are eventually triggered, and from Jamie (Tim Gibson), a ‘posh’ drama student who at least talks to her as a human being. And then there is Andy (Cameron Robertson), the father of the murdered boy visiting the memorial daily and holding a serious grudge against the filthy girl hanging around his cherished temporary monument.

Taking turns, the characters let us in on their world in monologues directed at the audience. Sam’s cynical view of Londoners and their creativity in avoiding each other (and herself, of course) is entertaining but you do wonder how she became homeless – alas, we don’t find out. At times, however, her analyses become overly sharp and descend into the annoying and clichéd. Her eloquence and relative optimism make her an atypical beggar, and much of the conversation between her and Jamie focuses on the fact that they’re not so different, after all. Jamie, then, reveals a little about his love life to us.

Andy has taken to alcohol after his son’s death and his violent outbursts against Sam by proxy involve Julia in this theatrical mosaic. His testimony is heart-wrenching. Hers, an insider’s view into the Met’s inner workings is less convincing and feels a tad too generic to be based on anything substantial. On the whole, the insights offered into these four very different people paint a picture of London as a whole: big, colourful, anonymous and brutal all at the same time.

Sometimes the dialogue is too dense with self-referential to-ing and fro-ing, but more often it sparkles a little and there are quite a few hearty laughs along the way. Steven Lally manages to lay bare his characters’ motivations and general psyche without deadlocking the story, which has a delectable and (I thought) fairly surprising denouement. Niall Phillips’s direction sees to it that the narrative gets the three-dimensionality it deserves.

With room for a laugh and a cry, Letters From Everyone tells its story of the big city with wit and pace, and holds its secrets till the very end. Good show.

Letters From Everyone is playing at the Drayton Arms Theatre until 20 December. For more information and tickets, see the Drayton Arms Theatre website.