Apparently a fire raiser is insurance jargon for an arsonist engaged in insurance fraud. And there are plenty of fire raisers from all levels of society in this movie which combines action/adventure with an interesting moral dimension.
Leslie Banks plays a slick insurance investigator who walks both sides of the legal line to make fast bucks in a corrupt industry. Much of the movie is spent in glamorous portrayal of his unscrupulous business activities and trendy lifestyle. One of the main strengths is the fast moving, cynical banter between the characters which creates a sense of their decadent lifestyles lived out against a background of unrestrained, completely amoral capitalism. No doubt this was a powerful image in the midst of the Great Depression when this movie was made.
But so much time is spent tantalizing us with the fruits of dirty business deals that it comes as a sudden surprise near the end of the movie to discover that there is a moral dimension. Because the ground has not been prepared, the main character's late struggles with his conscience may seem a little unconvincing.
For social history enthusiasts, there are some quaint historical shots of the London Fire Brigade and the British horse racing industry in action during the 1930s to lend some authenticity to this morality play.