The Hollow Man (The Three Coffins)

⚖The case for it

A man shot in a sealed room with no entrance or exit. Carr includes a chapter where his detective lectures on locked-room mystery types, a meta-fictional essay on the form itself. Purists consider it the highest achievement of the puzzle mystery.

— the canon

✕The case against

Carr's solution is so contorted you will finish the explanation chapter twice and still want a diagram. Characters exist to be moved around the trick, and the famous locked-room lecture halts the story so the author can grade his own genre. Ingenious machinery, attached to nobody you will remember.

— the honest librarian