Chapter 1 introduces the main questions to be tackled in the book, tracing a crime case from the discovery of a body to the verdict of a court. How do we generate initial hypotheses from sparse information? How do we develop our hypotheses as we gather new evidence? How do we make sense of a large body of conflicting evidence to reach a final decision? The crime case highlights the challenges we face: to explain what actually happened – the web of cause and effects that led to the death – but also to evaluate the evidence, assessing the many reports, claims and counterclaims. I argue that our minds are better prepared for explaining than evaluating.