Sometime after Stiletta left the family, Flattop Jr. was sent to live with his Aunt in South Dakota. She was a widow who worked outside the home, and as a result she had little time to monitor his activities. She would later note that Flattop Jr. started showing criminal tendencies at an early age.
Flattop Jr. was a budding mechanical genius who outfitted his super-car with devices like a television, fridge, stove, hi-fi record player, and running water. He was also a painter in the modern-art style, whose art was not considered that good (according to Tracy).
Flattop and Joe Period
Flattop teamed up with fellow juvenile delinquent Joe Period, resulting in a two-month crime wave that included the murder of Period's former boss "Nothing" Yonson. Period was captured by Tracy and the police. Flattop escaped with the loot stolen from Yonson's safe.
He hid out in a boarding house owned by Mrs. Skinner, who had a high school to college-aged daughter nicknamed "Skinny". Skinny entered one of Flattop's paintings into an art exhibition which won first prize. This drew the attention of Tracy and the police. Learning what she had done, Flattop killed her by throwing her off a roof. Her ghost (or his imagination of it) clung to Flattop's neck, which began to slowly drive him insane.
He took his car and hid out in an abandoned theater. Still tormented by the "ghost", as well as the rats that infested the building, he became increasingly desperate. Finding some theatrical supplies, he disguised himself and went to purchase provisions. He was noticed going into the derelict theater and the police were called. Tracy and Sam Catchem entered the building and Tracy climbed up a ladder to the roof, assuming that it was Flattop's only possible escape route. Flattop was still in the theater, however, which he set on fire, planning to make his escape in the confusion. Tracy was rescued from the burning building's roof just before the structure collapsed. Flattop's car was destroyed and he was assumed killed when a charred skeleton was discovered.
Escape into Madness
Using dental records, the skeleton was revealed to be that of Zeus Farnsworth, a retired actor who had been squatting in the abandoned building. Sam discovered evidence of a secret door through which Flattop had made his escape. He fled into the hills and went unseen for some time.
Flattop Jr. finally met his end at the hands of new policewoman Lizz. She was investigating the counterfeiting operation of Ivy, when she encountered Flattop purely by chance. She followed him through a secret entrance into Ivy's underground hideout, where Flattop pulled a gun on her. He was now emaciated, wild-eyed, and his hair had turned white. The "ghost" of Skinny still clinging to his neck, he intended to murder Lizz. Lizz shot first, killing him.
Legacy
Years later, when Angeltop came to town to promote her book, she defended her brother and their father saying that they were wrongfully persecuted, never brought to trial for their "alleged" crimes, and murdered by the police.
It was later revealed that the remains of Flattop Jr.'s car were found and restored (with additional features). The car came into the possession of Silver Nitrate who housed it at the Wonder Cars of the World Museum. Nitrate and his sister Sprocket used the car when fleeing the city.
The Nitrates retained possession of the car following their escape, though it was severely damaged after being submerged in a lake. The Nitrates (particularly Sprocket) restored the vehicle again, and were soon contacted by Stiletta Jones. Stiletta stated her desire to purchase her son's car, and the Nitrate's agreed. When Stiletta attempted to recruit Sprocket into a plot to kidnap Dick Tracy's infant grandson, the two women fought and Flattop Jr's mother was killed.
Notes
While he's remembered as "Flattop Junior", he was never actually called that in the original serialized newspaper story. There he was usually referred to as either "young Flattop", "Flattop's boy/son", or simply, "Flattop".
Flattop Jr. told Joe Period that he was 6 years old in 1944, during Flattop Sr.'s encounters with Dick Tracy. Therefore, Flattop Jr. was most likely born in late-1937 to early-1938, though technically he could have been born as recently as early-1939 and still have been 6 during part of 1944. This puts him in his late teens during his storyline in 1956.
Flattop Jr. never had any direct interaction with Dick Tracy. The closest he came was when Tracy was pursuing Flattop's car in a helicopter, when Tracy was present during his escape from "Nothing" Yonson's club, and when Flattop set the theater on fire after seeing Tracy climb up to the roof.
The idea that the ghost of Skinny was entirely a product of Flattop Jr.'s imagination does not explain why the ghost was shown waiting by the dead Flattop Jr. for a time and then taking off into the sky, rejoicing. This seems to be one of very few instances in Gould's narrative that death did not end a character's existence, as well as presenting what seems to be a genuinely supernatural occurrence.
Unlike his sister Angeltop (who was very protective of their father's memory), Flattop Jr. displayed no strong feelings about being the son of a notorious criminal. He expressed dislike for being called "Flattop's Boy", preferring instead to be addressed as "Flattop".
Flattop Jr. also does not express any specific animosity towards Tracy, only police in general. He therefore does not meet the criteria of a "revenge-seeking relative".
Flattop's actual first name (and, by extension, his son's) has been revealed to be "Floyd". This was apparently inspired by the real-life criminal Charles Arthur "Pretty Boy" Floyd, upon whom the character was originally based. Writer Mike Curtis has confirmed that Flattop Jr's first name is Floyd and that "Junior" is not simply a nickname that was applied to him.
Flattop Jr. appears on the cover of The Complete Dick Tracy Vol.17. The artwork comes from the cover of Harvey Comics' Dick Tracy Monthly #129. The artwork is by Al Avison, who prepared covers for many of Harvey's Tracy collections (with Chester Gould's approval). This makes Vol. 17 the first of IDW's Dick Tracy collections to feature artwork on the cover that was not produced by Chester Gould.
When the Flattop Jr. storyline was re-printed by Harvey Comics in 1959, the story was truncated and did not include Flattop's appearance at the end of Lizz's encounter with Ivy. The story seemed to end with Flattop drowning himself.
