I saw a rather dodgy print of this film, but luckily you can get just by recognising the voices: David Farrar as that other famous detective resident in London's Baker Street - "Sexton Blake"; Knyaston Reeves and Dennis Price could almost deliver this effectively on the radio! The plot is daft, but fun. The police are looking into the suspicious death of a mine owner, and together with amateur detective "Blake" are soon on the trail of a cunning Nazi conspiracy to invade Britain (well, Cornwall to begin with...)! Now, the plot is a string vest at a moth convention affair - loads and loads of holes. Sexton is caught by and escapes from the baddies with an almost monotonous regularity, but it is still quite an enjoyable yarn that pitches some decent character actors, a very basic script and some very simple (unintentionally comical at times) effects into the pot that simmers, rather than boils, well enough for 75 minutes before a suitably shambolic brawl at the end, with enough dynamite to sink the Lusitania. Still, if you are looking for a bit of low-grade mystery, you could do much worse.