Zagor and Chico cross paths with Mycroft, an agent of the British secret service, who dies before their eyes after revealing that the Weaver a mysterious criminal from Europe plans to seize absolute power in America. His strategy involves political and economic manipulation and the use of ninja assassins. Mycroft himself has fallen victim to one of them, who struck him with the “vibrating palm”, a deadly secret technique that causes death after a delayed period.
Soon after, Zagor and Chico face off against several escaped convicts from New York prison, recruited by the Weaver, as well as the invincible ninja warriors. During a fight, Zagor is hit with the “death that comes later” the vibrating palm, meaning he could perish in days or weeks, in unbearable agony…
Joining forces with Colonel Claymoore, Zagor and Chico get themselves imprisoned in New York’s Fort Concrete, nicknamed “the Gate of Hell”, where the Weaver is secretly recruiting his men and the conditions are brutal. After a staged escape, orchestrated by a member of the criminal organization, the two heroes must endure grueling initiation trials to be accepted into the group.
A man named Smith leads Zagor and Chico to the Weaver a hooded, shadowy figure who assigns them to carry out a dynamite attack. But Zagor turns the mission on its head: he destroys the enemy’s hideout and kills the ninja who had struck him with the deadly palm, thus neutralizing the lethal effect.
The Weaver manages to escape, only then do we discover that he was Smith all along but for now, his plans for conquest are crushed.
