Howard's reconstruction of a little-known 1946 Alcatraz ""crashout"" is a prefabricated screenplay of the tense 46 hours during which Kentucky bank robber Bernie Coy and his five companions attempted the impossible. A spectacularly bloody affair, the siege of The Rock gives Howard a chance to fill his gallery with desperadoes who have since attained near-mythical status: Machine Gun Kelly, Alvin Karpis, and Robert Stroud, the aging Birdman. All were lodged there at the time, though none was directly involved in the escape which included, besides Coy, ""Dutch"" Cretzer, a maniacal killer who also wrote poetry, and his half-wit sidekick. Howard has heightened the drama by depicting several of the others with considerable sympathy as ""Depression-era bank robbers,"" a tenable interpretation though Howard leans a bit hard on Dustbowl legends. Coy, a landscape painter and amateur psychologist, gets special regard as the only inmate to detect the single structural flaw in the Alcatraz gun-gallery--presumably one of the most secure spots in the prison--which made the crashout possible. The personal clash between Coy and Cretzer over leadership of the desperate little band provides much of the suspense; Alcatraz itself, that logistical marvel of a fortress, provides the rest. And for a backdrop there are two platoons of Marines firing bazookas as well as something of the grim history of that most forbidding prison.