[2] A later story arc explains, mostly through an extended flashback, that prior to his first meeting with Tracy, Pruneface led an espionage ring for the Axis powers to acquire a new secret formula for the deadly Xylon bomb, a non-radioactive explosive capable of devastating 10 city blocks.
Xylon was developed by Professor Roloc Bard, a mad scientist who was taken hostage by a fake swami named Yogee Yammi during an earlier storyline of the 1940s.
Pruneface kidnaps Bard and forces him to build several of the bombs, all of which but one is seized by Tracy and FBI agent Jim Trailer, hence the reason for the story being "suppressed" during the actual war.
This leads Tracy, Wendy Wichel and FBI Agent Jim Trailer to finding the last bomb hidden 10 blocks away from the Oval Office in an elderly Frieda Smith's basement.
Her empty house soon after receives a telephone call from Pruneface to set the bomb off, causing him and Dr. Freezdrei to change their plans and go back into hiding.
A masked man named "Captain Cure" would break into local TV programming and demand huge ransom money to prevent further outbreaks.
He was the target of a liberation attempt by his granddaughter Prunella and great-granddaughter Prune Hilda, but the plan failed at the last second, and Pruneface was sent plunging to his death from a mountain gondola.
In the 1943 Looney Tunes cartoon short Porky Pig's Feat by Frank Tashlin, Daffy Duck confronts the manager of the Broken Arms Hotel, pretending to be intimidated by something he said.
Another Looney Tunes short, 1946's The Great Piggy Bank Robbery by Bob Clampett, has Daffy (as "Duck Twacy") encountering a pack of Dick Tracy-style villains, including an obvious Pruneface parody called "Pickle Puss".