The English queen kept her cousin in captivity for 20 years and finally had her beheaded on a trumped-up charge of treason.
The English queen imprisoned her cousin for 20 years before beheading her, because she was seen as a threat to the crown. 
mnli hypothesis: The English queen imprisoned her cousin for 20 years before beheading her, because she was seen as a threat to the crown.  premise: The English queen kept her cousin in captivity for 20 years and finally had her beheaded on a trumped-up charge of treason.