Who has done it?

The detective story is sometimes called 'whodunit' because the reader has to work ......... who did it, who committed the crime.
in
out
off
over

The skill of course of the writing is how many times a reader can be sent up ......... alleys.
short
twisted
blind
long

Another way of putting this is how many red ......... the author can throw in the reader's path.
fish
sharks
cod
herrings

The idea is to keep the readers in a permanent state of ......... so that they never know what's going to happen next.
suspense
suspension
suspending
suspenders

As the plot ........., you find yourself agreeing with one character's solution and then another's.
undoes
unfolds
unties
unfurls

As a result you feel as if you are walking in a ......... since at each turning you come to a block end.
muddle
mess
maze
mist

One of the best known detectives is Agatha Christie's Hercule Poirot who uses what he calls his little grey ......... — his brains.
molecules
cells
particles
atoms

Invariably Poirots calls all the ......... together in the last part of the story.
suspicions
suspecting
suspected
suspects

One by one he ......... the innocent until finally the murderer is unmasked.
extinguishes
excludes
eliminates
exerts

The thing that always surprises me is the fact that the murderer bothers to take ......... in the final meeting.
partition
part
parting
parted