Mimi was the girlfriend of former gangster Lips Manlis. After Lips reformed and changed his name to "Bob Honor", he refused to associate with Mimi or his old gang anymore. Angry, Mimi arranged for the warehouse Bob was guarding to be burnt down so he would be fired. However, Bob wasn't on duty at the time and he even found the firebomb, making him a hero. They then resorted to kidnapping him, but while Mimi was out on an errand, Lips broke free, arrested the gang and started to haul them to headquarters. Mimi got back in time to see what was happening, so in an attempt to prevent it, she swerved her car in front of Bob's truck. The crash crippled her hand and she got away while Bob freed the captured gang from the burning truck and held them until Tracy arrived.
Mimi lost her hand and panicked, she went to dope-peddler Toyee's boat to hide-out. Toyee captured Dick Tracy and Pat Patton when they came to his boat after Mimi and tried to drown them, but they were rescued by Chief Brandon and Junior. Toyee and Mimi got away to Toyee's waterfront hideout, but Tracy quickly caught up to them. He caught Mimi and her gang and while Tracy arrested Toyee, Mimi managed to stab Pat and get away.
She got back to her place and had her gang kidnap Lips and drug him. While he was drugged, Mimi married him and then proceeded to convert Lips back to his old ways. Tracy enlisted Kitty Manlis, Lips' ex-wife, to find Lips and help him. When they arrived, Lips dropped Kitty and Tracy into a pit, making Tracy believe that Lips was once again crooked. Instead, Lips had done it to ensure Tracy's safety while he captured Mimi's gang. Realizing that she was beat, Mimi committed suicide by drinking a vial of poison.