Lupin III competes with the Kisugi sisters to steal a triptych of paintings that once belonged to their father, and which hold the key to a long-unsolved mystery.

The Cat's Eye sisters are once again aiming to steal the three paintings that once belonged to their father. Only this time, Lupin III is also after the same trio of paintings that is targeted by the three sisters. The paintings in question will also reveal a long-buried mystery.