Selkirk, a former Army officer, is bitter that he was never promoted beyond major. He breaks out two prisoners from the stockade of an Army base in Arizona. As Erskine and Daniels investigate, it's clear that Selkirk has an impressive collection of weapons. The two prisoners were labeled "incorrigibles" by the Army and their expertise includes demolition. Selkirk's target is a $750,000 Army payroll -- and he has the means and the intelligence to pull off the job.