In response to earlier provocation, Shibazaki is challenged with a riddle this time only he can solve in order to stop the bomb from blasting but at one condition, no one can cheat.

As Lisa recuperates at Nine and Twelve's place, Sphinx sets another bomb and posts another riddle, but things don't go as planned this time.

Five takes over the battle of wits against Nine and Twelve as Lisa tries to find her place in their group, but Shibazaki isn't happy sitting by idly.

The game is on at the airport and lives are at stake as Shibazaki and his team stumble into the middle of Nine and Five's dangerous game of chess.

Twelve goes off to save Lisa while Shibazaki and Hamura learn more about the Athena Plan and the Rising Peace Academy.

Things come to a head as Nine and Twelve go their separate ways and Shibazaki talks to Mamiya, the man behind the Athena Plan.

Tokyo is in a state of emergency as the country readies itself for the atomic bomb explosion. Will the mystery of Sphinx finally be solved?