This is one of the 'lighter' Charlie Chan movies - almost TOO light, considering that what everybody's after here is the formula for a new, enormously powerful atomic bomb... But let's leave that aside; the film is meant as a clever and entertaining detective story, and that's what it is.
It all starts when a detective disguised as the secretary of nuclear scientist Wyans is killed VERY mysteriously while sitting in front of his typewriter: there were no less than six suspects around (and one more suspicious than the other: a gun runner, a smuggler, a Nazi propagandist, a fake countess, a girl who denies her descent from Czechoslovakia...), there was only one shot heard, but two bullets fired (one in the victim's heart, and the other one in the wall) - and no trace of a gun anywhere! Now who could solve THIS mystery, AND find the very cleverly hidden formula, with the only evidence being a bottle of Chinese 'Red Dragon' ink? Only Charlie Chan, of course!
And amidst all the hard and dangerous detective work, Tommy and Birmingham's cousin Chattanooga (played by tall, thin Willie Best, the exact opposite to short, round-faced Mantan Moreland in appearance, but almost equally marvelous at playing 'scared') of course find time to entertain us with their clumsiness both at detecting and at romancing - and we get to see even Charlie himself doing a rumba with a pretty young Chinese artist! But the BEST laugh is kept for the final scene - see for yourself...
