What plan do Sir Andrew and Lord Tony discuss when they are left alone at the Fisherman's Rest?

The two men first discuss how the Scarlet Pimpernel smuggled more people out of Paris ,

"He crossed over to England two days before we did. He had escorted the party all the way from Paris, dressed--you'll never credit it!--as an old market woman, and driving--until they were safely out of the city--the covered cart, under which the Comtesse de Tournay, Mlle. Suzanne, and the Vicomte lay concealed among the turnips and cabbages. They, themselves, of course, never suspected who their driver was. He drove them right through a line of soldiery and a yelling mob, who were screaming, `A bas les aristos!"

Both men then stoop near the fire to read their new instructions. They hear a soft sound, and all of a sudden they are apprehended by masked thugs who take them away and read their secret papers.