A cure for Alzheimer's would be worth billions. And well worth killing for. Simon Ayot is an Englishman working for Revere Partners, one of Boston's top venture-capital firms. The firm's star investment, worth millions of dollars for each of its partners, is BioOne, which is working on a cure for the disease. Frank, one of Simon's bosses and his father-in-law, is found murdered at his summer house...