What was Tanis' excuse for where he had been?

Tanis' excuse for where he had been was that he had been captured by the Dragon Highlord. He explained that the Highlord thought that he was one of his officers, and asked him to perform the duty of escorting him to the awaiting troops which were stationed on the outskirts of the town. Tanis explained that he had to do as the Highlord asked, in order to avoid raising suspicion and then he returned back as soon as he could.