Knock, knock, knock.

"Penny?"

Knock, knock, knock.

"Penny?"

Knock, knock, knock.

"Penny?"

Penny walked over to the door. "Yes, Sheldon?" she called out.

"Can I come in?"

"Are you a zombie, Sheldon?"

"Of course not. How you could ever think that I, Dr. Sheldon Cooper, the greatest mind of my generation, would be outsmarted and cornered by one of the undead never ceases to amaze me."

Penny rolled her eyes. "Yes or no, Sheldon. I know you know the rules, 'cause you're the one that made them."

"Fine, fine. No, I'm not a zombie. Now can I come in?"

It took a moment to unlatch the multiple deadbolts but she finally opened the door. "Sure thing, sweetie," she greeted him with a smile. "Just do it quick." Sheldon did as he was told, something that was still one of the strangest and most disturbing parts of this new world.

Leonard looked over from his position at the window. The table beside him, where he and Penny had eaten so many dinners, was bare except for a small, electrical box. One press of the button on top and a circle of strategically placed buckets in the surrounding neighbourhood would mix ammonia and bleach, sending out a wave of toxic gas sure to take out even the toughest of zombies. "Did you find anything?" he asked.

"Unfortunately no," Sheldon replied as he sat down on the chair, the one he'd arranged so carefully years before as his spot in her apartment. "I was hoping to make it to the drugstore but the only way to make it would be through brute force and without Penny that just wasn't an option."

Penny smiled. "Who knew junior rodeo skills were so transferable? Did you get close enough to see if there was anything worth taking?"

Sheldon shook his head.

"It's still the most likely place for there to be anything useful," Amy said as she walked out from what was once Penny's bedroom. "We're getting low on explosives."

"Not to mention food," Leonard added.

"I know, I know," Penny muttered, frowning. "Right. We should radio the others and see if they want to go on a raid with us. Sheld - ..."

Naturally, Sheldon already had the radio in his hand. "Batcave, this is Titan Tower, do you read me? Over."

"Right," she said, shaking her head. She looked over at Leonard. "Have I mentioned lately how awesome it was that you had a ham radio just lying around."

He grinned. "Who knew geek skills were so transferable?"

A crackle drew her attention back to the radio and, a moment later, Bernadette's voice came through the radio's one working speaker.

"This is the Batcave, we hear you, Titan Tower."

Penny shook her head slightly, wondering again how she had let the boys talk them into those callsigns. But there wasn't time to think about that, she could think about that tomorrow. Right now, it was time to kill some dead things. She took the transmitter out of Sheldon's hand and spoke into it herself.

"We're thinking of putting together a raiding party to go to the drugstore on the South Arroyo Parkway," she said. "Think you guys could lend us a hand?"

"What was that, they want to start a band?"

"No, Ma! They want us to lend them a hand!"

"A zombie hand?"

"Right, because that's what everyone needs these days, zombie hands, since they're just so hard to come by."

"Well, how am I supposed to know that, it's not like ..."

The yelling continued but mercifully became quieter as a door was shut. "Sorry about that," Bernadette said. "This house seems to be getting smaller every hour we're stuck here but at least it's still safe. And we've gotten most of the stuff out of Howie and my apartment too. Anyway, I'm sure we can help out, though we'll have to wait till Raj gets back. He had to take Cinnamon out for a walk."

Penny groaned. "He's still doing that?"

"He says she's quite fierce around the undead."

"I'm sure she is. Alright, let us know when he gets there."

"Will do."

She passed the radio back to Sheldon, who immediately added "Over and out."

Penny sighed and met Amy's eyes as they both shrugged in unison. Penny had to laugh at that and remind herself how important it was to find things to laugh at, even if it only lasted a few seconds before she remembered the zombie apocalypse.

They didn't have to wait long before the radio sputtered on again. "Raj just got back," Bernadette told them. "He says it's clear around us so we can head out in a moment. We'll go to the usual rendezvous point."

"Over and out," Howard added a moment later, causing Penny another small gigglefest. Oh, these boys.

Her boys. And her girls too, she thought as Amy walked past, putting together the supplies they would need for this mission.

Penny walked over to Leonard and peered out the window with him. "See anything?"

"No," he answered, shaking his head. "There haven't been any zombies here all week. I think maybe you put the fear of God in them last time. Or at least the fear of a second death."

Penny nodded. "Okay. You know what to do if anything gets close while we're gone."

"Trust me," he said softly, gazing up into her eyes, "my finger won't be leaving the trigger."

"Good. Just as long as you wait long enough to make sure it's not us you're blowing up."

"I will," he said, looking around once more before standing up and heading to the door. Sheldon and Amy were standing nearby and Penny joined them, as Leonard started turning open the locks.

"We were able to make another batch of grenades but there's not enough drain cleaner or aluminum foil left for any more," Amy told her.

"I'm running a bit low on ammo too," she admitted. "We'll do our best to avoid any fights, at least until we meet the others at the comic shop. Hopefully they'll have more on them."

After the last deadbolt turned, Penny leaned over to Leonard and kissed him lightly on the lips.

"Be careful," he said softly.

"I will."

"And?"

Penny smiled as she reached for the shotgun sitting beside the door, lifted it up, and cocked it. "I'll make sure I shoot first."