Even for the best mystery authors, there’s some readers who’ll likely guess it right in the opening line based on the spent cartoon-themed condom that’s hanging from the ceiling fan. Thus, the trick is to make sure it’s a good read EVEN once the mystery isn’t no longer a real mystery. You’ll want some red herrings, of course, along with some irrelevant details – for the lazy writer, the red herrings can be from changing the plot half-way through