Arrest Bulldog Drummond

John Howard plays the adventurer hero of the title and H. B. Warner portrays his friend Colonel Nielson of Scotland Yard. This time the case involves an experimental ray machine that can cause explosions at great distances -- and the man behind it all is Rolf Alferson, played by veteran British character actor George Zucco (who made a career out of playing mad scientists, mad cultists etc. -- the operant word being "mad").