If Italy leaves the euro, it will be late on a Friday night.

Government officials will have planned the move in the utmost secrecy, telling their European partners only that same evening while simultaneously ordering the shutdown of banks and financial markets to prevent a stampede of capital out of the country.

This is "Italy's Plan B," an eye-popping contingency scenario drawn up by the team at a website specializing in economic issues, for how the eurozone's third-largest economy should go about returning to the lira if necessary.