  We present $B$ and $V$ light curves of a large stellar flare obtained with
the Wide Field Camera at the Isaac Newton 2.5-m telescope (La Palma). The
source object is a faint ($m_V=21.38$) foreground star in the field of the
Andromeda galaxy, with its most probable spectral type being dM4. We provide an
estimate of the total flare energy in the optical range and find it to be of
the order of $10^{35}$ erg. The cooling phase of the large flare shows three
additional weak flare-like events, which we interpret as results of a
triggering mechanism also observed on the Sun during large coronal mass
ejections.
