What If the Presidential Election in 2016 Ends in an Indecisive Three Way Race

People are already speculating on the possibility of a three way race.  One scenario is Senator cruz or Governor Kaisic is nominated by the Republicans and Trump runs as a third party candidate.  Former Secretary of State Hillary Clinton is nominated by the Democrats and is indicted before the election. (If Clinton were indicted before the convention, the pols would desert her for Vice President Biden.)

Let us further speculate that none gets a majority of electors in the electoral college.  What happens?

The House of Representatives votes and each state gets one vote. (Article II Section 1.) There is a possibility of deadlock, but presumably multiple ballots are possible. The Senate only gets involved in the case of a tie for Vice President, the president of that chamber.

If I remember right, John Quincy Adams was the last president so elected, although Andrew Jackson, the Trump of his day, had more popular and electoral votes (neither anywhere near a majority.)

Adams was certainly worthy of the office. I can not make the same judgement about his successor. Unfortunately, in the next election the populist, rabble-rouser Jackson won, financed by the crony capitalists of the day (mostly country bankers.) The "man of the people" had as his running mate, the well heeled New Yorker Martin Van Buren. The demon of the Trail of Tears promptly drove the economy into America's first recession and the the first of the banking crises we have suffered from every ten years since (in my professional judgement, no coincidence.)

Jackson was the godfather of the expansionist policies that hoped to extend slavery to ever newer lands. Professional historians frequently rate him among our five greatest presidents. Greatest is not best and he hardly exemplifies the virtue that the Founders believed essential to the Republic's success. The German word for "great" is "gross."

The moral: do not believe every judgment you read in the history books.