Ageing "Uncle Felix" (Melvyn Rawlinson) isn't feeling up to snuff, so consults his physician who tells him that he hasn't long for the world. He's been an explorer and archaeologist all his life and has decided to leave everything to the British Museum - whether they want it or not - save for one mysterious box that is to be bricked in, permanently, to the cellar of the home which he is leaving to nephew "Archie"…