"Capt. Marvel Introduces Mary Marvel": Billy is hosting a quiz bowl at WHIZ Radio with three young contestants. During a commercial break, Billy receives an urgent letter from Sarah Primm requesting his presence. He immediately goes to see the dying woman, who tells Billy about his twin sister.
- It happened! I changed! I feel strong... powerful... my, what a lovely costume too!
Appearing in "Capt. Marvel Introduces Mary Marvel"
- Marvel Family
- Mister Scarlet (Cameo)
- Mrs. Bromfield (Mary's foster mother) (Mentioned only)
- Percy Pill (First appearance)
- Sarah Primm (Only appearance; dies) (Flashback and main story)
- Achilles (Mentioned only)
- Atlas (Mentioned only)
- Hercules (Mentioned only)
- Mercury (Mentioned only)
- Solomon (Mentioned only)
- Zeus (Mentioned only)
- Ariadne (Mentioned only)
- Aurora (Mentioned only)
- Hippolyta (Mentioned only)
- Minerva (Mentioned only)
- Selena (Mentioned only)
- Zephyrus (Mentioned only)
Synopsis for "Capt. Marvel Introduces Mary Marvel"
Billy is hosting a quiz bowl at WHIZ Radio with three young contestants. During a commercial break, Billy receives an urgent letter from Sarah Primm requesting his presence. He immediately goes to see the dying woman, who tells Billy about his twin sister. When the Batson twins were orphaned after their parents died in a car accident, Primm had substituted Mary for the baby girl of a rich family she nursed for, who had suddenly died, and sent Billy to an orphanage. Primm gives a locket broken in half to Billy. Mary, Primm tells Billy before dying, wore the other half of the locket.
After the quiz is over, Billy recalls that one of the contestants, Mary Bromfield, wore a broken locket, so he and Freddy Freeman trail Mary's limousine in their super-powered forms of Captain Marvel and Captain Marvel, Jr.. Mary is kidnapped for ransom by thugs, prompting the two Marvels to intervene, save her, and knock out the kidnappers.
Captain Marvel then learns that Mary's locket matched his own, and that she was indeed Billy's sister. The Marvels reveal their secret identities to Mary, who thinks if, since she is Billy's twin, she could become a Marvel by saying the magic word "Shazam."
The kidnappers wake up and gag Billy and Freddy, preventing them from saying their magic words. "Oh no," exclaims Mary, "Billy can't say 'Shazam!'" Shortly after saying the word, inadvertently, a magic beam hits Mary Bromfield, and she turns into a super powerful version of herself. She then defeats the bandits alone and frees Freddy and his brother.
Appearing in "Capt. Marvel Fights a Nightmare"
- Nightmare creatures from Dreamland
- Prof. Archimedes Bram (Single appearance)
- Prof. Bram's robot butler
- Prof. Bram's robot chef
- Prof. Bram's robotic watchdogs
- Prof. Bram's Imagino-Reproducer
Synopsis for "Capt. Marvel Fights a Nightmare"
- Synopsis not yet written.
Appearing in "Captain Marvel and the What-Not Adventure"
- The Duval Gang (Single appearance)
- Brutus Duval
- The Society for the Collection of Obtuse What-Nots (Single appearance)
- Mrs. Thorntree
- Professor Totter (Single appearance)
Synopsis for "Captain Marvel and the What-Not Adventure"
- Synopsis not yet written.
Appearing in Captain Kid: "Tanks a Lot"
- Neighborhood kids
- United States Army Tank Corps
- Earth-S (retcon)
- "The U.S. Killer", a motor vehicles built by the kids out of scrap metal
Synopsis for Captain Kid: "Tanks a Lot"
- Synopsis not yet written.
Appearing in "Capt. Marvel and the 3 Wishes of Tim Tucker"
- Professor Murder (First appearance)
- Tim Tucker (Single appearance)
- A genie
Synopsis for "Capt. Marvel and the 3 Wishes of Tim Tucker"
While Billy Batson is on a fishing vacation his guide, Tim Tucker, fishes an old bottle out of the lake and breaks it open, revealing a genie who grants him three wishes before flying away. With Billy and Steamboat disbelieving it was more than "smoke and thunder" they just saw, Tucker makes a wish for a golden touch like King Midas (but learning from Midas's misfortune, wishes for it in only one hand). He tries it out on their boat, but the simple Tucker doesn't anticipate that a gold boat can't float and Billy transforms to save them.
Tucker is rash in using his power and crooks soon appear and try to rob him, but Captain Marvel arrives and beats them up. When Cap advises Tucker to wish away his golden touch or things will only get worse, this only reminds him that he has another two wishes coming, the second of which he uses to become the most important man in the country. This soon overwhelms Tucker, with every important issue being handed to him to be decided. Captain Marvel again arrives and clears the room for him, but again ignoring Cap's advice to cancel his wishes, Tucker uses his last wish to be like Captain Marvel. Then, he'd be able to handle anything.
The new second World's Mightiest Mortal ignores Cap's warning that it's not fun or simple being in his shoes, and after being constantly ignored Cap leaves Tucker to find out for himself the mistake he's made. Fearing more than one Captain Marvel getting in their way, numerous criminals try to kill him, which Tucker easily withstands, but soon falls into the series of death traps of Professor Murder. The bad Professor declares that the underworld stays after Captain Marvel night and day, and Tucker escapes but realizes that his troubles are worse than ever with every crook, tyrant and villain around out to get him now. Especially since he hasn't lost his golden touch and people still want him to make important decisions for them. The ghost of Shazam then appears, and since Tucker is technically under his protection as something of a second Captain Marvel, the wizard magically revokes the three wishes. Time rewinds back to the fishing trip, but Tucker's powers are gone.
- Capt. Marvel Introduces Mary Marvel is reprinted in Shazam! #8, Shazam!: From the 40's to the 70's, The Shazam! Family Archives Vol. 1 and Shazam!: A Celebration of 75 Years.
- Also featured in this issue of Captain Marvel Adventures was "Killer in the North" (text story) by Carl Formes
- During Billy's radio show, "The Mental Marvel Quiz Program," a question by C. Beck is read: "Who is Captain Marvel?"
- Discuss Captain Marvel Adventures Vol 1 18 on the forums
- Cover gallery for the Captain Marvel Adventures series
- Images from Captain Marvel Adventures Vol 1 18