On the second floor, in 1588, her son Henri III used not poison but a dozen men armed with swords and daggers to do away with his archrival, Duke Henri de Guise.
Henri III poisoned Henri De Guise. 
mnli hypothesis: Henri III poisoned Henri De Guise.  premise: On the second floor, in 1588, her son Henri III used not poison but a dozen men armed with swords and daggers to do away with his archrival, Duke Henri de Guise.