MacGyver and his former college professor Atticus have discovered a coin bearing the Greek letter Sigma in ruins of Mycenae and barely escaped near-death by triggering a booby trap. Atticus, a convinced scholar who believes the legend of Atlantis is real, thinks this artefact is the key to solving Solon's riddle (which he first heard of in dome caves of Exeter where early Christians hid from the Romans). When the University board does not grant him the funds to pursue an expedition, Atticus teams up with MacGyver to go to the Balkans. There, they find themselves in underground catacombs looking for a hidden artefact, while a civil war ensues over their heads. They are discovered by resident militia, who take the relic, the Ark of Solon, from them. Atticus and MacGyver manage to escape with the Ark back to England, where MacGyver meets Kelly, an old friend and now research assistant who helps him analyze a residue found on the box. The dating of the Ark appears to be of the first century BC, the Roman era, although the Ark is supposedly dated in the Iron age. Atticus is disappointed when, upon opening the Ark, the supposed Staff of Wisdom within, is not there. The Ark gets stolen from the museum by Zavros,a renegade general working together with Lord Cleeve. Cleeve is a wretched treasure hunter who once worked with Atticus, Zavros hopes the treasure will fund his private war in Macedonia. Atticus informs MacGyver and Kelly that the unveiling of the treasure of Atlantis is closely linked to a cosmic phenomenon, that cycles every 500 years, due in two days from now. This energizes the mechanisms of ancient Atlantis technology to unlock their treasures. Back in Exeter, MacGyver, Atticus and Kelly discover the Staff of Wisdom, but are kept from returning by Cleeve and Zavros. Atticus appears to be on their side. They leave MacGyver and Kelly tied-up, but by MacGyver's genius wit, they escape once more. They return to Cleeve's estates to get both artefacts and flee, with the remoursefull Atticus, to Thera (Santorini), the volcanic island believed to be the site of Atlantis. There, they find an injured Simon, Kelly's grandfather. Now they know Cleeves and Zavros are ahead of them. Gaining an access near temple ruins at the volcanic peak, they have to solve some more puzzles in order to bypass the Gates of Hades, where they find the charred body of Zavros in the crematorious corridor behind the doors. They run into an armed Cleeves. When they reached the main chamber, they find the petrified Solon sitting with his book of platinum ponce cards. They are just in time to witness the cosmic spectacle above the open crater, where they witness the allignments of the planets, representing the ancient Greek gods who now 'march in rank'. They activate a hydraulic steam-powered computer with the remaining platinum pieces that drives up the platform with treasure chests. Cleeves is in rage when he founds out that the content are just scrolls. MacGyver realizes that the treasure was all about preserved, written knowledge. Solon's riddle mentioned the treasure could control the minds of men. After disposing of Cleeves, the trio narrowly escapes the inside temple by means of a winch and rope, while the temple below them engulfs in debris and flames by the exploded hydraulic engine. Written by a