City banker Roger and his acquisitive wife Arabella represent the new money living in Pepys Road, South London, whilst elderly widow Petunia, recently diagnosed with a tumour, has lived there all her life. Quentina, the street warden, faces deportation back to Zimbabwe when her visa runs out and Muslim Ahmed runs the corner shop, his two younger brothers who work with him having different attitudes to their religion. One day they all receive postcards stating We Want What You Have, though D.I. Mill can do little to help. Having lost his expected bonus due to duplicitous young co-worker Mark Roger is stunned when Arabella leaves him at Christmas, requiring the services of nanny Matya. Petunia's young grandson Smitty persuades his mother to spend Christmas with her but Christmas morning brings an unpleasant surprise for them all.

Arabella returns after Christmas and seems less concerned about Matya's presence than Roger's decreased bonus, even when Roger takes the nanny to a charity auction and spends almost two thousand pounds on a picture for her. Quentina is taken to a detention centre to await deportation whilst D.I. Mill calls an ineffectual meeting regarding the postcards as now dead rats are being pushed through letter boxes instead . Four months later Petunia dies and daughter Mary calls in quarrelling Polish builders Piotr and Bogdan to renovate the house, Bogdan making a spectacular discovery. Ahmed and is family are not happy when his mother suddenly arrives from Karachi but worse is to come as they are all arrested by armed police.

As the police investigation into the 'We Want What You Have' campaign leads them in an unexpected direction, DI Mill hopes to secure a confession.