The first edition of the Catechism of the Catholic Church included the statement that it is not wrong to keep information from those who have no right to it. The second edition eliminated this qualification much to the detriment of the text, making it ambiguous and insinuating that one must, under any and every circumstance, reveal truthfully anything demanded even by those with no right to the information in discussion. Hence, if an unjust aggressor is asking about the whereabouts of an innocent victim, you are (according to the Catechism) acting immorally by misleading the aggressor.
Intelligence and common sense tell us that we have a moral right and duty to protect an innocent from an unjust aggressor. New Advent has a good article on “lying” where it presents the different schools of thought on the subject. One school does not allow lying under any circumstance, while the other recognizes that it is sometimes necessary when a party involved has no right to the truth. In such circumstances, one must follow what the conscience dictates.