A “stalking horse” a screen traditionally made in the shape of a horse behind which a hunter can stay concealed when stalking prey.
Sometimes this strategy is used in business too.
You may be dealing with someone you consider harmless, whilst unwittingly dealing with a competitor or enemy.
By letting down your guard you open yourself to attack.
Be paranoid. Stay on your toes.
Beware the stalking horse.
Also published on Medium.