The plane crash mystery
You rack your brain for ideas to stop the virus. Then you have it - that lightbulb idea. "Maybe..." "What?" "Well, since a virus is software, not hardware, you can't see it. But, maybe, if you hack into all the devices that have the virus, and get it out of all of them, the virus would die out." "That's a great idea, but how would you get all of the devices? Their everywhere". What do you do?