The details of the example of the ‘murderer at the door’ – as it is commonly, if inaccurately called – are more complicated than most interpreters assume. This chapter is dedicated to the details of the case, many of which surface only in the light of other eighteenth-century versions of the story. Does the would-be murderer know that the person hiding his intended victim knows about his murderous intentions? Why are the options of the person asked about the victim’s hiding place restricted to yes or no, and how would this restriction work in practice? What are the reasons or motives of someone who intends to lie to a would-be murderer? And what are Constant’s ‘intermediate principles’, which he introduces to defuse the problem case? The chapter also explores Johann Gottlieb Fichte’s discussion of the case in his 1798 System of Ethics. Fichte and Kant agree that lying is not a legitimate option; but Fichte is by far the more radical moralist of the two.