Brave and the Bold #123 (1975)

After helping stop crooks from robbing a bank, Batman is asked to arrest Bruce Wayne, who is wanted for fraud and murder. Batman goes to Istanbul to capture Wayne, who is there to purchase the Neji, an expensive totem from the Kahari tribe of Africa. Wayne is there to purchase it to bring it back to it's native tribe that has erupted into violence. There he's confronted by Batman.... Who really turns out to be Plastic Man. It's revealed that the real Bruce Wayne was looking for the ideal candidate to pose as him while he was out of town securing the totem when he came across Plastic Man -- who had become a homeless bum following their last encounter, and offered him the chance to play the role of the caped crusader. An offer which Plastic Man agreed to, and hence the reason for this bizarre turn of events. Taken back to Gotham City, Bruce Wayne is found guilty of his crimes and locked up in prison. There he's visited by his "lawyer" who turns out to be Rex Mason (AKA Metamorpho) is disguise. He gives Bruce a spare Batman costume and the two break out of prison and begin looking for Plastic Man. Their search brings them to Ruby Ryder Inc, where Batman tries to see if Plastic Man has rekindled his old flame with Ryder. The hunch turns out to be true, Ryder having learned of Plastic Man's recent assignment posing as the Batman allowed her to manipulate Plastic Man once more. She had used him to frame Bruce Wayne to eliminate him as a bidding rival for the Neji, which she wishes to claim for her own. Batman decides to steal the real Neji, and leaves Metamorpho to pose as the statue when Ryder claims it hoping to record evidence indicting her of her crimes. With her caper almost in the bag, Ryder intends on poisoning Plastic Man to eliminated him as well having decided his usefulness had come to an end. Metamorpho's cover is blown when Ryder's cigarette smoke causes him to cough. The two malleable men battle over the tape recording of Ryder's confession, however Metamorpho prevents its destruction. When Ryder's goon tries to shoot Plastic Man, he realizes he's been used again and he and Metamorpho work together to capture Ryder. After Ryder is turned over to the police, Batman encourages Plastic Man to continue his career as a super-hero. Later, as Bruce Wayne, the Batman returns the Neji to its people, and restores order to their land.