Locusta, the reader will remember, was the woman whom Agrippina had employed for the murder of her husband, Claudius. She was still in custody as a convict, being under sentence of death for her crimes. She was in the charge of a certain captain named Pollio, an officer of the Prætorian guard. Nero sent for Pollio, and directed him to procure from his prisoner a poisonous potion suitable for the purpose intended. The potion was prepared, and soon afterward it was administered. At least it was given to certain attendants that were employed about the person of Britannicus, with orders that they should administer it. The expected effect, however, was not produced. Whether it was because the potion which Locusta had prepared was too weak, or because it was not really administered by those who received it in charge, no result followed, and Nero was greatly enraged. He sent for Pollio, and assailed him with reproaches and threats, and as for Locusta, he declared that she should be immediately put to death. They were both miserable cowards, he said, who had not the firmness to do their duty. Pollio, in reply, made the most earnest protestations of his readiness to do whatever his master should command. He assured Nero that the failure of their attempt was owing entirely to some accidental cause, and that if he would give Locusta one more opportunity to make the trial, he would guarantee that she would prepare a mixture that would kill Britannicus as quick as a dagger would do it. Nero ordered that this should immediately be done. Locusta was sent for, and was shut up with Pollio in an apartment adjoining that of the emperor, with directions to make the mixture there, and then to administer it forthwith. Their lives were to depend upon the result. The poison was soon prepared. There was, however, a serious difficulty in the way of administering it, since a potion so sudden and violent in its character as this was intended to be, might be expected to take immediate effect upon the taster, and so produce an alarm which would prevent Britannicus from receiving it. To obviate this difficulty, Pollio and Locusta cunningly contrived the following plan.