This book describes the Taurus project--a 500m project to automate settlement systems on the London Stock Exchange. Begun in 1986, it was eventually abandoned in 1993. How was it that a major project promoted by the Stock Exchange, supervised by committees, advised upon by two major consultancies, staffed by an experienced technical team, could go wrong? Why was the decision to abandon the project not taken earlier? Written in the context of theories of decision-making, the book both tells an absorbing story and adds to our understanding of decision escalation.