The soltoxin gas attack was an assassination attempt using a soltoxin gas grenade against Aral Vorkosigan in the early days of his Regency, just before the official outbreak of Vordarian's Pretendership. Perpetrated by Evon Vorhalas in revenge for Aral's refusal to save his younger brother Carl from execution, it was also indirectly controlled by Vidal Vordarian. The windows of Vorkosigan House were subsequently force-screened to prevent such events from happening again.