Olrik has obtained a telepathic helmet. Blake, on his trail, reaches Easter Island. With Mortimer's help, he figures out the riddle of the Moais - or giant statues - that dominate the island's landscape.

Mortimer meets a colleague who holds the secret to the Philosopher's Stone. However, a mysterious client has hired Olrik to find interfere with these plans.

Olrik has plans to steal the necklace of Marie-Antoinette and make a deal with the collector who will collect the insurance fee.

Olrik attempts to steal radioactive matter; Blake and Mortimer discover the buried civilisation of Atlantis, which is at war against the wretched offspring of the Mayas.

Blake is accused of being a traitor and goes on the run, but not before giving Mortimer instructions to remember an address; Mortimer begins an investigation to clear his friend's name.

Mortimer makes a daring escape from the police with the help of Virginia Campbell; Blake reveals Olrik's location to Mortimer, and the duo figure out he's up to no good.