The third detective novel is called 'Das Versprechen' ('The Promise') and takes place in post-war Zürich. In a story within a story, a famous writer on a book tour meets a retired police Captain who, not thinking much of the way his metier is portrayed in fiction, decides to educate the novellist in real police work. While driving the writer back to Zürich, the policeman relates a story about a former employee who tried to act like a character in a novel and instead found his whole existence crumbling around him.
The policeman's story centres on Lieutenant Matthäi and his insistence on continuing the search for a little girl's murderer, even after the main suspect, a travelling salesman with a prior conviction for sexual molestation, admitted to carrying out the attack, before hanging himself in his police cell. At first, his colleagues refuse to believe that a mistake has been made; however, through the use of ever-so-slightly unethical tactics, Matthäi manages to lure the real murderer into his carefully-laid trap. And that's where real life starts to have an influence...
Matthäi's inhuman persistence in the face of wide-spread scepticism hangs on the promise he made to the mother of the murdered Gritli Moser. Unable to ignore the doubts he harbours about the confession of a convenient scapegoat, Matthäi forces himself to continue the hunt for the real murderer, despite the effect the chase is having on his life. In the end, a prediction made by a psychologist he consults about the case comes chillingly true; unable to find the murderer, he only finds madness.
As mentioned above, Matthäi was actually on the money, and the real murderer is tempted to stalk the cute eight-year old girl that Matthäi uses for bait (told you it was unethical...), so where does it all go so wrong? As in Dürrenmatt's earlier novels, it is luck, or rather misfortune, that provides the twist in the tail. While little Annemarie sits waiting for her fateful encounter with a child molester (and half the Zürich police hide in the bushes), the potential murderer has already met his fate. At the end of the book, we learn that he died in a car crash on the way to the secene of the crime... After a week of stake-outs, the police lose patience and leave Matthäi to his fate; for the poor unfortunate genius, this consists of drinking, smoking and waiting for a murderer who will never appear.
For such a short book with a fair amount of action, the writer is able to build the tension to unbearable levels, with the reader feeling the urgency of Matthäi and his captain as they lie in wait for the murderer. Annemarie sits and waits, the policemen hide and watch, Annemarie sings the same song over and over again, nobody comes, Annemarie plays with her doll... for days the policemen watch and wait until, finally, one of them cracks; then, the remaining detectives begin to shout and scream at the poor girl, demanding she tell them all she knows. Under the unbearable pressure of the wait, the girl's protectors become the ones she needs protection from.
This tension is also evident in the final part of the book when Frau Schrott, an old lady on her death bed, summons the captain to tell him something important before her death. Through her meandering nothings about her family and her various marriages, she stretches the story (and the captain's nerves) to breaking point, leaving the reader breathless in her slow, measured progression to the part about the murderer. Only when she reveals the truth about her husband, the murderer, and the events leading up to his death, does the reader finally learn that Matthäi was both right and terribly, terribly wrong.
It is Matthäi's character which reinforces the effects of his investigation. Unable to adapt to unforeseen events, he continues in the path he has taken, which should, logically speaking, lead him to his goal. However, life has a funny way of meddling with even the best-laid plans; while fictional detectives usually get their man in the end, in real life luck can intervene to stop you achieving your goals, no matter how well you have prepared.
At the end of the novel, there are some very poignant lessons to be learned from Matthäi's downfall. Firstly, expect the unexpected. Life cannot be micro-planned; something will always get in the way of your best intentions. Secondly, and perhaps more importantly, be very careful with what you say. Never, ever, make a promise that you may not be able to keep. Who knows what may happen to you if you can't keep your word...