Absolute Gamble

Before the incident where the Justice League battled the Secret Six, Barry Allen, the League member known as The Flash, was searching for Wally West, a young man he knew who disappeared in front of his very eyes when Barry intervened in a shooting at his school. Barry has been looking for the boy, who he thinks also has super-speed powers like him, ever since; he even joined the League because Superman promised to give him information that could help him on this (which he delivered). After escaping The Rogues, Barry's partner Chester Rulkin pulled up solid evidence of Wally's possible location, but The Flash had to help the JL deal with the Secret Six before he could act on this.
Barry traveled to the city of Independence, MO to find and talk to the family who took the picture that Wally was caught in. He talked to Jay Garrick, an elderly gentleman, who took the picture with his adult son and two young grandchildren while vacationing in Paris, France. Jay and his son tell Barry about a recent string of child abductions in France they had heard about while they were overseas, and they had to cut their trip short out of fear for the children's safety. Barry boarded a plane to Paris to investigate further; he could have run across the water without falling in, but he doesn't have anything to protect his clothes and personal items from the velocity while he carried them. After getting into a hotel, Barry poses as an investigative journalist from the states to talk to Paris Police Department captain Noelle Avril about the recent child abductions. She gave Barry all the info she could give him, but they were unaware that one of her men was eavesdropping...
That night, Barry was in his hotel room when he noticed, out of the corner of his eye, a man with a sniper rifle aiming at his room. Calculating the assassin's reaction time, he dodged the shot and, in the milliseconds it took him to reload and refocus himself, Barry got into his Flash costume and caught the killer on the adjacent roof. The sniper, later identified as Tommy Monaghan, refused to tell him anything... until a minute later, when he was dangling on the top of the Eiffel Tower, about a mile from the hotel. Tommy tells the Flash that he works for Roulette, a dangerous figure in the French underworld, and a dirty cop in their employ told them about a “reporter snooping around, asking about snatched kids”, so they sent him to kill the guy. Tommy told him where to go and who to ask about “The House”. Flash thanked him for this info, and dropped him... then he appeared at the bottom so he could catch Tommy in a cyclone generated by the Flash running in a circle.
Back in his civilian garb, Barry made his way to the red-light district of the city, and recognized one of the cops from the precinct there, but in plain clothes; figuring he may be the dirty cop who tipped off Roulette, Barry quickly knocked him out from behind, with nobody noticing, and swapped clothes with him after hiding his unconscious body in a dumpster. The cop had a cheat sheet on him, which had a password and an address; Barry reached the door at said address and told the shady doorman “Fair Play”, which made him allow Barry to enter. Inside the House, Barry found throngs of people crowded around steel cages, where vicious fighters were beating the hell out of each other. The heaviest concentration of patrons was on the central cage, and they were all chanting a name: “Impulse”. Barry got to the cage and saw... Wally! He was moving at high speeds and fighting a muscular brute... and winning! When the young man defeated the opponent, named “Bomba”, the people who bet on him cheered and others who bet on the thug booed. A woman in red latex, with half-shaved brown hair, sunglasses, and tattoos, came up to the stage with a microphone and a white cat on her shoulders; Barry asked who she is and one of the patrons said it's Roulette!
Roulette announced the “final round of the tournament”, the “fight you've all been waiting for... Impulse Vs. Rampage!” An African woman in a latex one-piece with a mohawk stepped into the cage to fight Wally. As the fight progressed, Rampage seemed to get stronger and stronger, eventually countering Wally's speed and snapping his leg. Barry had enough, so he ran away, got in his costume, and ran back as fast as he could so he could drop kick the cage door off and knock out Rampage. The audience booked it out of The House as fast as they could, but Roulette remained. She snapped her fingers, and other House fighters stormed the area from the back rooms with firearms. Flash got Wally in his arms to run out with him, but he was halfway towards the back exit when he registered that the boy said “You Can't!”
Barry ended up in a darkened room, where he let Wally on the floor; the boy lifted up some of his hair to where some of it was shaven off... and there are scars and a red light blinking under his skin. “If I go too far away from the House, it'll explode!” Then the Flash noticed more blinking red lights in the darkness; he turned on the lights to see many children, of various ages, races, and genders, shackled to the wall, all of them with bombs implanted in their heads. Barry told them that he'll be back soon; he got to the other side of the door, rubbed his hands together at high speed, and used the heat from the friction to melt the locks so Roulette's goons couldn't get to the children. One by one, The Flash hunted down the thugs and cage fighters loyal to Roulette and took them out. He found Roulette in her office and ran for her, but Rampage clotheslined him. Flash and Rampage did battle. The woman looked like she was going to win until Flash realized she was absorbing kinetic energy he was generating to become more powerful; he overloaded her cybernetic implants that allowed her to do that and the surge knocked her unconscious. Barry assailed Roulette and demanded to know how to deactivate the bombs that could kill the children; she said that he'll never find the failsafe remote. He looked at her cat, which rolled on his belly... revealing fresh surgery scars. Flash took off his gloves, took the cat, and stuck his fingers in his mouths, causing it to barf up the remote.
In the end, Roulette, real name: Victoria Shang, and those loyal to her were arrested, along with any of the audience members the police could round up. The children were all rushed to the hospital to have the disabled bombs surgically removed. Soon after, Wally and the other kidnapped children were able to return home. Barry found him, now he just needs to know how he gained super-speed like him...

In Victoria's jail cell, a voice called to her in the dark.

“I gave you back your shriveled, little life for you to find the shards of the Shieda Blade, and you've wasted it in pursuit of trivial currency and unnessecary sport. I've, in all honesty, considered giving you a final chance in light of this... but I don't appreciate what you did to poor Teekl...”

The next morning, the French police found Victoria dead in her cell.

Notes:
* The city of Independence is supposed to be the equivalent of “Keystone City”, just as LA is to “Central City”.
* Jason “Jay” Garrick was a World War II veteran, and his leg was crippled in the line of duty while taking back Iwo Jima.
** After the war, in the 50s, Jay helped form an equal rights and liberty coalition called “The Justice Society of America.”
*** Other founders of the JSA include Alan Scott, Albert Pratt, Rebecca Tyler, Wesley Dodds, and Khalid Ben-Hassin.
* Captain Avril of the Paris PD is based on mainstream character “Fleur-De-Lis”.
* Roulette's assassin Tommy is basically the same as “Hitman”, except without the alien superpowers.
* The pass phrase “Fair Play”, used to enter The House, is taken from mainstream Roulette's great-uncle, the heroic “Mister Terrific”.
* Wally was made to take the nickname Impulse when Roulette forced him to fight for The House.
* Roulette bought illegal cyborg technology from Circe's gang to convert Kitty Faulkner into Rampage. Rampage came into being because “Impulse” bested too many brawlers in the ring and Roulette needed to mix it up.
** Roulette also bought from Circe the explosives they used to control the children.
** That's right; Circe's back.
* Other fighters for The House include: Blindspot, Coldcast, Deathblow, Four of Spades, Green Dragon, Osprey, and Promethea.