Shadow of the Naga (Nak Prok, นาคปรก), directed and written by Phawat Panangrasiri, was made three years ago but because of its storyline (violence against monks and gun-toting monks) was thought to be unreleasable here. Thanks to a new movie rating system in Thailand the film has now been passed as suitable for people aged 18 years and over and will be on general release soon.
The title comes from a Buddhist legend in which a mythical serpent, a Naga, attempted to disguise itself as a human so it could be ordained as a monk. The Buddha saw through its disguise and told it that by doing good works and meditating it would eventually be reborn as a human and could then become a monk. This legend is one of the explanations for the question "Are you a human being?" in the Buddhist Ordination Ceremony.
In this movie three bank robbers bury their loot in the grounds of a temple. Later they return to collect their money but find that a new temple hall has been built over the burial site. They decide to ordain as monks so that they can stay at the temple while they work out to retrieve the money. The movie is a combination of thriller, action, and refelctions on the consequences of our actions. From the trailer and clips that I've seen it looks like it's well worth seeing.