Many people are curious as to why thriller writer James Patterson feels obliged to write so many novels in tandem with other (less well-known) writers. After all, runs the argument, Patterson is so comfortably ahead of most of his rivals in both sales and popular acclaim that it is a mystery as to why he feels the need to dilute the Patterson brand any further. Of course, a part of this reaction against the co-authored Patterson novels is due to a feeling that while Patterson"s name may be in the larger font on the jacket, it may be his co-author who has done more of the work. This is not the place to debate such arguments, but with the appearance of Postcard Killers, a new element has been introduced into the mix. In this case, Patterson"s co-author is not a writer-for-hire with whom the reader may not be very familiar, but a considerable novelist in her own right -- the talented Swedish writer Liza Marklund, already celebrated for her own highly individual novels (which are, in fact, quite unlike those of James Patterson). So what results have this ill assorted duo come up with in their first collaboration? Jacob Kanon is a New York detective who has decided to take the grand tour; but for different reasons from most people. As he visits some of Europe"s most beautiful and historic cities, his response is very different to that of the average tourist. Everything Jacob sees is refracted through a dark search; he is looking through the eyes of the murderer of his daughter, Kimmy, who was killed with her fiancée in Rome. Jacob is aware that other murders have followed this, all involving young couples in such cities as Salzburg, Athens, Madrid and Paris. The one element that connects the various killings is a postcard sent to a local newspaper. It"s up to the New York detective to join forces with a Swedish journalist, Dessie Larsson -- in receipt of a postcard from Stockholm -- before more couples die.The partnership in the novel here -- between an American and a Swede -- is obviously echoed in the literary partnership that produced the book itself. Interestingly, while reading Postcard Killers, it is not always clear cut where Patterson ends and Marklund begins -- perhaps a deliberate strategy on the part of the co-authors. Certainly, the book is markedly different from most portmanteau Patterson novels, though some Marklund fans may wish that she had more of a marked input into the novel. But perhaps the principal market here will be admirers of James Patterson, and they are likely to feel that they have got their money"s worth. --Barry Forshaw