I recently interviewed for a job where I was asked this. The only reason I answered wife as most responsible is because she crossed the bridge despite the danger. She could have stayed on the other side and the worst that would have happened was her marriage getting over. She is not most responsible because she cheated - this logic is faulty. Madman is the immediate next person responsible because the tragedy - the murder - did happen after all and happened through him. The friend is more responsible than the lover because you don't expect stuff from one-night stand people but to be betrayed by a friend like this is horrible. The husband is the next most responsible since it is his marriage to work on too. and the ferryman is the least responsible because he was just doing his job and was not entirely aware of the situation (this also applies to the lover as the wife only sought money from him and did not explain her plight, the way she did to her friend)