Calculatedly ruthless. This expression comes from the days when it was commonly believed that blood rules the temper and was boiling hot when one was excited and ice-cold when one was calm. The French call it sang-froid, a term taken over in English with the same meaning. Thus Byron wrote of Don Juan, “Cross-legg’d with great sang-froid among the scorching ruins he sat smoking.” In more recent times Truman Capote used the term as the title of a detailed account (1965) of a deliberate act of murder.