The Last Alarm

The Last Alarm is a 1940 American Monogram Picture film directed by William West and starring veteran character actor J. Farrell MacDonald.

Jim joins the arson investigation at the bureau, having had some experience when he was in the fire brigade. Spectroscopic analysis of wood found at the scene of the last big fire reveals that part of the burnt time bomb box Jim found was maple wood, so he, Henderson and Roberts scour the city for the maker of the boxes and who they sold them to.At another big fire, Jim comes across a statue of Vulcan Roman god of fire which the arsonist dropped, it being his inspiration. The arsonist gets it from Jims unlocked car where he put it. Mention of this statue later and the fact that Frank and Joan saw it in the antique shop window provide a strong lead so they get a search warrant. They do not find any bomb making equipment but Jim finds wood shavings which later analysis reveals to be the same wood as that used for the time bomb box. ........

Source: Wikipedia