Double Down is the thirteenth episode of the second season. It was released on 13 January 2006.
Charlie and the team investigate a murder at a casino, a location which brings to light a dark, glossed-over corner of Larry's past. The murder itself also proves deeper and darker than it first appeared.
The image comes from gambling, specifically blackjack, where the player is allowed to increase the initial bet by up to 100% in exchange for committing to stand after receiving exactly one more card. It is often done when splitting aces, face cards or tens. It is often used in the media to refer to a public figure reinforcing, rather than backing away from, a previously stated position, especially one seen as precarious.