In a flashback episode, the gang ponders the future of the Ted, Robin and Barney love triangle. Meanwhile, Barney accepts a series of challenges from Lily and Robin.
Jane and the CBI are called in when a retired star quarterback (guest star Craig Bierko) is presumed dead following a car explosion.
When a double homicide involving two young journalists who are investigating a story about gold fraud occurs on the eve of St. Patrick's Day, the CSIs must find the clue at the end of the rainbow. (TV-14)