Edmund Mortimer
In February 1405, during the rebellion of Owain Glyndŵr, Constance herself instigated a plot to abduct the young Edmund Mortimer, 5th Earl of March, and his brother, Roger Mortimer, from Windsor Castle, apparently intending to deliver the young Earl, who had the best claim to the throne of any of Henry IV's rivals, to his uncle Sir Edmund Mortimer, who was married to Glyndwr's daughter. The young Edmund Mortimer and his brother were recaptured before entering Wales. Constance implicated her elder brother, Edward, in the plot, as a result of which he was imprisoned for 17 weeks at Pevensey Castle, but was eventually restored to Henry IV's favour as well as the seized property of Constance who had been sent to Kenilworth Castle.