In pre-World War II Tokyo the American newspaper editor Nick Condon (James Cagney) working for an English-language daily paper aimed at the American business community is given a document relating to Japan's foreign affairs which could have political ramifications if found. He meets up with Iris Hilliard (Sylvia Sidney), a woman who wants to secure the document even if it means dealing with the Japanese secret police and their threats.
You can stream Blood on the Sun (1945) free and legally on OldReel, via the Internet Archive.
Yes — it is in the public domain and can be watched and shared freely.