Prince Shuysky now enters. Boris insults him, accusing him of conspiring with Pushkin, an ancestor of the poet. However, the prince brings grave tidings. A Pretender has appeared in Lithuania. Boris angrily demands to know his identity. Shuysky fears the Pretender might attract a following bearing the name of Tsarevich Dmitriy. Shaken by this revelation, Boris dismisses Fyodor. He orders Shuysky to seal the border with Lithuania, and, clearly on the edge of madness, asks Shuysky whether he has ever heard of dead children rising from their graves to question Tsars. Boris seeks assurance that the dead child the prince had seen in Uglich was really Dmitriy. He threatens Shuysky, if he dissembles, with a gruesome execution. The Prince describes the ghastly scene of Dmitriy's murder in a brief and beautiful aria ("In Uglich, in the cathedral"). But he gives hints that a miracle (incorruptibility) has occurred. Boris begins choking with guilt and remorse, and gives a sign for Shuysky to depart.