  The Frauchiger-Renner argument aims to show that `quantum theory cannot
consistently describe the use of itself': in many-party settings where agents
are themselves subject to quantum experiments, agents may make predictions that
contradict observations. Here, we introduce a simplified setting using only
three agents, that is independent of the initial quantum state, thus
eliminating in particular any need for entanglement, and furthermore does not
need to invoke any final measurement and resulting collapse. Nevertheless, the
predictions and observations made by the agents cannot be integrated into a
single, consistent account. We propose that the existence of this sort of
\emph{Rashomon effect}, i.e. the impossibility of uniting different
perspectives, is due to failing to account for the limits put on the
information available about any given system as encapsulated in the notion of
an \emph{epistemic horizon}.
