Grandma's Suitcase

“Do you need help with that, ma’am?”

The elderly woman smiles. “Why, yes. Thank you, dear.”

“Is this your bus?”

“Put it in the middle. It’s the best spot.”

He boards the bus, but she doesn’t follow. She hobbles behind a concrete pillar and dials a number. The detonator engages, and her suitcase explodes.