I guess that means no clues
I believe that the missing men referred to are Jean-François de Galaup, comte de Lapérouse and his men sailing on La Boussole and L'Astrolabe.
On 20 January 1788, the First Fleet arrived in Botany Bay. The British believed they were completely isloated from any other European presence. Just four days later however, Philip Gidley King recorded in his journal:
'...two Strange Ships were seen standing in the Bay ... we judged them to be the two Ships under the orders of Monsieur de la perouse.'
La Perouse's ships sailed out of Botany Bay in March 1788. The British lookout on South Head saw them leave. This was probably the last time the French expedition was seen by Europeans.
In 1791, when La Perouse had not returned to France or made any contact by dispatch, the French government sent out a search party. It was commanded by Rear Admiral Joseph Antoine Bruni d'Entrecasteaux and consisted of two ships, Recherche and Esperance.
I guess we are looking for the location where this search party landed.