Somewhere deep underground was a place lit only by magical torches. Its walls, ceiling, and floor were all covered in cold, hard metal and stone, and the only entrance and exit was through a gate at the end of a tunnel, which led out to a path running alongside a mountain. The path led up to another entrance to a more familiar place to most criminals: the Canterlot Dungeons. This place beneath even the damp cobblestone of the more well-known prison was a high security facility. Many guards and other obstacles sat between that and a little cell in block A.
Block A had several related guests: all Diamond Dogs of the same pack. There crime was one that should have landed them in the prison above. The nine of them, ordered around by a hound named T-Bone, had attempted to dig into the Royal Palace to loot basically anything that had a shine to it. Typical Diamond Dog motivations. They just wanted to see pretty sparkles. Their arrest, however, was not smooth. Several Royal Guards were injured in the fighting. Seven were either killed on the spot or died of their wounds. The courts made sure the pack would pay for their crimes and sentenced them to this newly built facility for highly dangerous criminals, beneath a whole mountain. Surrounded by steel, the dogs wouldn't be able to dig their way out. They would spend the rest of their pathetic lives crammed in these cells, far from the sunlight and far from moveable earth. Tartarus.
One cell, A-4, held one of the pack of extreme note. It wasn't the leader of the pack, T-Bone, who would scamper away from the guards whenever they so much as looked at his cell. It wasn't Max, his enforcer and right hand, who reportedly flung the body of one of the guards around like a doll, striking anything that got in the way – including her own friends. It was a rather humble-sized Diamond Dog named Rudie. At the request T-Bone, he had concocted the plan for the heist. He knew just where to dig, but made some mistakes. For his failure, the other eight wanted his head to roll. They couldn't do him in on the spot, and even now were hesitant about committing the act, given what he did.
When the Guards had breached the tunnel behind them and the others began fighting, he instinctively lashed out with his claws and gnashed his teeth. This was all it took for him to manage to finish off four off them. The "credit" for their deaths fell squarely on him when they were standing in the court. Many of the Guards from that night were disgusted by the look on Rudie's face during the trial: wide eyed and confused. He knew what he had done, so why the look? A few days in the cell made things clear to the guards in the prison at least: he was scared. Terrified, maybe. Whether it was at what he had done, or the death threats from his neighbors that came daily during the first few months, or simply the extent of his punishment was anypony's guess.
Even so, Rudie was still relatively active. For a while, at least. During the last two months – nine in total now – he had started becoming withdrawn. He would sit all the way back in his cell during the day and curl up in the shadows at night. There were no more barks of protest whenever one of the others threatened him out of boredom. Now he was beginning to eat less. It was subtle at first, but over time the amount of food left on his plate went from noticeable to appearing as if he outright refused to eat. The guards minded as the chopped meat was unpleasant to handle, and they didn't even want to touch the stuff. Now, it was breakfast time. He wouldn't eat it, of course. It would be the third day in a row without a single nibble; It was getting to the point they were considering dragging him out and force-feeding him. That action wouldn't be approved of unless he skipped out on lunch and dinner later. For now, the fish would have to be left for him.
Two guards, one pushing along the food cart, slid the tray of food through the flap of cell A-3. The Diamond Dog within practically leapt at the meal. One of the guards shook his head in disgust at the sounds coming from beyond the steel door.
"And here we are," the one pushing the cart said as they moved in front of A-4. "I told you about this one, right rookie?"
"Is this the one that's been starving himself?" The other asked, picking up a tray. "The one with the body count?"
"Yeah. Goes by the name Rudie. I think he's depressed, but we can't do jack about it. He might starve at this rate."
"An' he better!" A gruff shout came from A-5. "That pups gonna wish he do--"
"Can it in there!" The guard banged his baton against the door. The deafening noise made many of the other prisoners flinch and cover their years.
"Is that why he's not eating?" The rookie asked.
"Just shove the tray in so we can say we followed reg," the senior said impatiently.
The rookie took the tray of fish, lifted the flap, and slid the tray in. The sound of the tray's movement was different after a moment. Curious, he gave a quick glance through the bottom flap.
"Rookie, get your head away from there! You're lucky he's too busy starving himself to--"
"Blood!" The rookie yelled before standing up. "There's blood on the floor!"
The senior narrowed his eyes. "Are you certain? Stand back, we're getting this open. He may be chewing his way to the afterlife." He reached for his keys and approached the door.
The other Diamond Dogs began clapping, cheering, and howling at the announcement. It may not be in the way they wanted to do it, but Rudie was getting his just desserts anyway. T-Bone, in A-10 across the hall, watched through the small grating in the his cell door, practically drooling all over it.
The senior guard turned his key and slid the door open. There was some blood on the floor, but it looked like it had be smeared there to make it seem like much more. He didn't have time to contemplate the stain; Two rear paws in the chest launched him backwards into the rookie and the cart, and they all went tumbling away. Rudie was getting out.
Not being the size of a tank like that grunt T-Bone proved to be an advantage to the beagle. He dashed out of his cell, fish in his mouth, and sped to the entrance to the block with his former pack gnashing furiously in their cells behind him. The guard at the gate pulled his baton and swung, but Rudie was too fast. He got a hold of the baton and bashed the guard, a solid thwack rendering him unconscious and dropping him. The other two were just starting to get up as he used the "sleeping" guards key on the gate, which promptly opened. The warning bells went off as he left Block A and dashed for the lobby on all fours.
Rudie expression through the whole thing was calm as could be, even with a fish in his mouth and a multitude of guards swinging at him. As the exit loomed into view, a pair of unicorn guards appeared and snapped a net right in his path. He was moving too fast to avoid it, so he simply lashed a claw out and carved through the ropes. Had they used cables, he wouldn't have made it. He roughly shoved the two guards together and into a wall before dropping them in the path of pursuers and making a break for it.
The exit was just a simple door, and he only had to turn the handle before escaping into the sunlight. Guards were already coming from the path above, and the ones behind him were getting closer. With nothing but a ledge and a hope ahead of him, Rudie went with instinct.
He jumped. A few moment of free fall later and he launched his paws into the side of the mountain, scrapping the rock and earth with ease as he slowed his descent and began to dig, and he was gone. By the time pegasi guards could investigate his tunnel, he had finished it and made his escape.