1981. Marguerite, a brilliant scientist, is abruptly dismissed from her research project. Her new director, the deceitful André Capelle, intends to use her prototype antenna to contact a Machiavellian intelligence from another world.

Kagami drags Marinette to Tokyo to help the Stellars defeat a new supervillain, but Marinette soon realizes her friend has another, untold reason for this trip to Japan.