Here's the first reel of The Trail of the Octopus, a pulpy serial photoplay from 1919. Watch as Carter Holmes (Ben Wilson), master criminologist, and Ruth Stanhope (Neva Gerber), niece of Dr. Reid Stanhope, the discover of the Sacred Talisman of Set (a.k.a. the Devil's Trademark), are drawn inexorably into the clutches of a sinister land octopus (who sadly is only symbolic of the plot and makes no appearance outside of the intro and an advert where he grabs the whole cast):

The 15-part serial follows Holmes and Ruth as they must track down nine daggers that will unlock a rock vault in which Dr. Stanhope hid the Sacred Talisman, which they want to destroy to stop a shadowy conspiracy of cultists and racist stereotypes from attempting to kill Ruth. From a review:

The producers [at first can't] seem to decide on whom they wanted the main villain to be. First it's a group of devil worshipers and their female leader, then we find out she works for this other guy, then we find out he is an agent for this other Arabic bad guy who lives in "the orient." Well that guy in the orient actually works for yet another guy over in the orient, who is a Fu Manchu knockoff. Perhaps he really is the final leader of all the bad guys? There is also a mysterious masked man known as Monsieur X who pops up in the story every so often, but he's someone else completely. Whew!

Serial Squadron, who are in the process of transferring the films to DVD from the only known prints, have a project overview. You'll have to wait until Spring to buy the DVD set if you want to see the semi-complete serial (episode 9 is lost). Here are some posters for the episodes: