  We study the entropy of quantum-dot system in contact with a symmetrical CFT
bath living on the boundary of pure AdS3 black hole. The q-dot is localized at
the centre of bath system of finite size. We first determine the exact location
of the `information horizon' for q-dot and then obtain corresponding
generalised entropy of q-dot plus bath system. It is done by finding codim-2
time extremal curve whose end point uniquely determines the information horizon
of localised q-dot system. By including the (bulk) entropy contribution of the
information horizon the Page curve for the radiation follows. These results can
be easily generalized to higher dimensional cases as well.
