In 1943 a body was washed up on the shore of Spain that appeared to belong to Major William Martin. With the body were documents subtly indicating that the Allied landing in Europe would take place not in Sicily, as the Nazis were expecting, but in Sardinia.
In fact William Martin was a fiction, down to the obituary that duly appeared in the newspapers. But the Germans fell for the ruse.
The body in the water, or Operation Mincemeat as it was referred to by the British security forces that dreamed it up, contributed to a change in the course of the war. But who did the body really belong to and how did he die?
The story is pieced together in this latest show from Cardboard Citizens, a professional theatre company working with homeless and ex-homeless people as creators, participants and audiences. It is a remarkable piece of theatre: multilayered, passionate and as innovative as anything on offer on the London stage. It doesn't just deserve a much wider showing, it demands one.
Its success lies not in the script or the performances, which are excellent, or the fact that it is a good story that needs telling, but rather in the way the way form and content reflect each other. Mincemeat is a journey into the past, into death and into identity, and it is performed in different locations in an old derelict building.
As you wander through empty rooms and down cracked staircases you begin an expedition into the past in which the lives of the dispossessed and the forgotten are rediscovered. One of the best scenes recreates the Tilbury air-raid shelter where many of London's poorest people took up residence during the war.
There is no nostalgia here, just a clear-eyed acknowledgement that the dispossessed, the poor, the mentally troubled and the homeless are always with us and the powerful will simply ignore them or, if they believe there is a need, wipe them from history.
There is no better reminder that behind every statistic is a face and behind every dead body a person and a story. One that in this case makes you angry and makes you cry.