  We consider a Hayden \& Preskill like setup for both maximally chaotic and
sub-maximally chaotic quantum field theories. We act on the vacuum with an
operator in a Rindler like wedge $R$ and transfer a small subregion $I$ of $R$
to the other wedge. The chaotic scrambling dynamics of the QFT Rindler time
evolution reveals the information in the other wedge. The holographic dual of
this process involves a particle excitation falling into the bulk and crossing
into the entanglement wedge of the complement to $r=R \backslash I$. With the
goal of studying the locality of the emergent holographic theory we compute
various quantum information measures on the boundary that tell us when the
particle has entered this entanglement wedge. In a maximally chaotic theory,
these measures indicate a sharp transition where the particle enters the wedge
exactly when the insertion is null separated from the quantum extremal surface
for $r$. For sub-maximally chaotic theories, we find a smoothed crossover at a
delayed time given in terms of the smaller Lyapunov exponent and dependent on
the time-smearing scale of the probe excitation. The information quantities
that we consider include the full vacuum modular energy $R \backslash I$ as
well as the fidelity between the state with the particle and the state without.
Along the way, we find a new explicit formula for the modular Hamiltonian of
two intervals in an arbitrary 1+1 dimensional CFT to leading order in the small
cross ratio limit. We also give an explicit calculation of the Regge limit of
the modular flowed chaos correlator and find examples which do not saturate the
modular chaos bound. Finally, we discuss the extent to which our results reveal
properties of the target of the probe excitation as a "stringy quantum extremal
surface" or simply quantify the probe itself thus giving a new approach to
studying the notion of longitudinal string spreading.
