An Italian security expert with a former KGB agent at a sushi restaurant in London has tested positive for radioactive material. Guest: Edward Lucas of the Economist

This week's topics include the Iraq Study Group and the candidates who are eyeing the presidency. Guests: John Harwood of the Wall Street Journal, CNBC and Ana Marie Cox of Time.com

Felipe Calderon takes office as Mexico's new president amid charges from opponents that he stole the election. Meanwhile in Venezuela, Hugo Chavez retains a commanding lead going into Sunday's election. Guest: Shannon O'Neil, Council on Foreign Relations

In light of the reason poisoning of an ex-KGB agent, a story that has garnered international attention, we review how people are killed with mysterious substances in mystery fiction.

The real life story of a man who arrives in New York with $75 in his pocket, begins singing in a restaurant where the director of the Santa Fe Opera is dining and...well you can imagine the rest of the story.