Diabolik: Who Are You?

Diabolik and Eva devise a scheme to target the wealthy Countess Wiendemar. Diabolik kidnaps Gabriella Bauer, the countess's banker, so Eva can impersonate her and steal valuable ancient coins. Their plan culminates with Diabolik arriving in a getaway car after the theft.

During the bank heist, armed men storm the scene unexpectedly, killing Countess Wiendemar in front of Eva. They steal the coins as part of their loot, disrupting Diabolik and Eva's plan and introducing unforeseen dangers.

Inspector Ginko is assigned to investigate the robbery. Alongside Sergeant Palmer, he begins gathering clues and quickly identifies the mastermind behind the crime as Diego Manden, who hides behind his legal career.

Using their disguise skills, Diabolik and Eva follow Manden to learn about his routine. They locate his private mansion, setting the stage for a potential confrontation to recover the stolen coins.

Diabolik attempts to infiltrate Manden's mansion believing him to be alone but gets ambushed by Manden’s gang. He is captured and taken to a basement, where he reunites with Ginko, who had tried a similar plan earlier.

Ginko reveals he was also captured during his attempt to break in. He confesses that Palmer was also involved in an earlier rescue plan and was murdered, leaving Ginko and Diabolik to face their doom alone.

Ginko asks Diabolik to share his past before their deaths. Diabolik recounts his orphaned childhood, his upbringing on a criminal island by King, and how he murdered King to take his place and begin his own criminal career.

Distraught over Diabolik's disappearance, Eva discovers a news broadcast hinting at Ginko's fiancée, Altea di Vallenberg. Eva disguises herself as Altea's former stylist to meet her and devise a new rescue plan.

Eva, in disguise, infiltrates Manden's lair by luring his men outside with Diabolik's bulletproof car. Inside, she eliminates the guards and captures Manden, who is sedated with a tranquilizer dart. Eva then reveals her true identity and works to free Ginko and Diabolik.

Eva successfully rescues Ginko and Diabolik, but soon tricks and subdues both Altea and Ginko. Altea finds herself freed but also disappointed that Eva and Diabolik have left, although Eva secretly returns her necklace as a gesture of gratitude.

Following the rescue, Ginko kisses Altea and declares his intention to marry her, suggesting a new beginning after the chaos. This marks a moment of resolution for their relationship amidst ongoing dangers.

The film concludes with Diabolik and Eva disguised as an elderly couple planning yet another theft. They successfully rob an auction and Eva reclaims her iconic pink diamond, symbolizing their unbroken criminal partnership.