Rogal Dorn knew something was wrong. He had materialised on one of the lower decks of the great battle-barge that was the flagship of Horus. The Emperor was not with him. Nor was the Angel Sanguinius. The Custodian Guard, the Emperor's sworn bodyguard, surrounded him and instantly adopted a defensive posture. 'What has happened?'one of them asked Dorn.'Where is the Emperor?' 'It seems we have been tricked. Horus has worked some fell magic to separate us,'the primarch replied. ''We must locate the Emperor at all costs, and do it quickly,'he added.