THE MAN ON THE BLUE is Shamrock Ireland, wanted in three states and trying to get to the Arizona border ahead of the latest posse. Six dry days later, he finds himself rescuing a stranger from cruel death at the hands of a woman. The stranger turns out to be Sheriff Lobell who is looking for a hardcase to do a dirty job; the woman turns out to be the sister of the man Lobell wants killed. The sheriff thinks he has found his man in Shamrock, not knowing that Shamrock has guessed Lobell's secret: one more killing and Sheriff Lobell would attain a fortune in dead man's gold. Would Shamrock be the instrument of the sheriff's gain and the woman's loss?