Peter Arno is the grandson of Clive Arno, a museum curator and explorer who, in the 1960's, discovered a chest full of mystical coins bearing the likenesses of gods of various pantheons. Each coin would grant Arno powers similar to the deity whose likeness appeared on its face. Using these coins Arno became an adventurer who the media often referred to as "Captain Action", occasionally accompanied on adventures by his teenaged son who also made use of the coins. In the early 1970's Arno retired from his adventurous lifestyle and died some years later in a an accident at an archaeological dig. Clive's son took over his father's work and had a son of his own, Peter, who would also grow up to be an archaeologist like his father and grandfather.
The coins themselves seemed to have lost their power of the years and were stored safely away in the Arno family's attic until just a few years ago. During the events known as the "War of the Gods" the coins' power returned and Peter's father used them to battle a group of god's that had gone mad because of the witch Circe's manipulations. In the end Peter's father was killed protecting a group of innocent bystanders. Afterward Peter gained possession of the coin's and has occasionally used them to combat various threats he has encountered in his travels.
Recently Peter encountered the new Enforcers of Justice when the alien traveler Seker awakened in Superior City. Peter helped communicate with the alien, who now accompanies Peter on his expeditions across the globe and goes by the name Ankh.
Peter Arno possesses the mystic coins found by his grandfather over thirty years ago. Each coin bears the likeness of a deity belonging to one of the many pantheons of gods on Earth and is imbued with a fraction of that god's power. By wielding a particular coin, the Peter gains the power of that god. While he cannot carry all of the coins with him, Peter often has several useful ones on his person at all times. His favorites include the coin of Hercules, which gives him super-strength, Hermes for superhuman speed, Heimdall for enhanced senses, and Zeus which grants him power over lightning and storms. Peter himself has no powers but he is very intelligent and physically fit.