CHAPTER TITLES: 1) The Doomed City, 2) The Shadow Attacks, 3) The Shadow's Peril, 4) In the Tiger's Lair, 5) Danger Above, 6) The Shadow's Trap, 7) Where Horror Waits, 8) The Shadow Rides the Rails, 9) The Devil in White, 10) The Underground Trap, 11) Chinatown Night, 12) Murder by Remote Control, 13) Wheels of Death, 14) The Sealed Room, 15) The Shadow's Net Closes.
The first chapter is three reels long (approximately 30 minutes) which is roughly half the running time of a typical "B" feature at that time.
In other mediums, the Shadow has the power to cloud men's minds, so they cannot see him. In this serial, though, it's the villain who, through scientific methods, becomes invisible to those around him. The Shadow is just a guy in a black cape and mask, who is terribly mysterious.
Jack Ingram (Flint) and Robert Fiske (Stanford Marshall) plus Kit Guard (Clark) (uncredited) would later work with VIctor Jory in The Green Archer.