  The exploration of topological electronic phases that result from strong
electronic correlations is a frontier in condensed matter physics. One class of
systems that is currently emerging as a platform for such studies are so-called
kagome magnets based on transition metals. Using muon spin-rotation, we explore
magnetic correlations in the kagome magnet Co$_{3}$Sn$_{2-x}$In$_{x}$S$_{2}$ as
a function of In-doping, providing putative evidence for an intriguing
incommensurate helimagnetic (HM) state. Our results show that, while the
undoped sample exhibits an out-of-plane ferromagnetic (FM) ground state, at 5
${\%}$ of In-doping the system enters a state in which FM and in-plane
antiferromagnetic (AFM) phases coexist. At higher doping, a HM state emerges
and becomes dominant at the critical doping level of only $x_{\rm cr,1}$
${\simeq}$ 0.3. This indicates a zero temperature first order quantum phase
transition from the FM, through a mixed state, to a helical phase at $x_{\rm
cr,1}$. In addition, at $x_{\rm cr,2}$ ${\simeq}$ 1, a zero temperature second
order phase transition from helical to paramagnetic phase is observed,
evidencing a HM quantum critical point (QCP) in the phase diagram of the
topological magnet Co$_{3}$Sn$_{2-x}$In$_{x}$S$_{2}$. The observed diversity of
interactions in the magnetic kagome lattice drives non-monotonous variations of
the topological Hall response of this system.
