In Deep Waters, Zac's mission is in one of the deepest oceans in the world. Even GIB's subs can't handle the depth. But the enemy has invented a new sub that can dive deeper than ever before. Can Zac find the enemy, and protect the top-secret information stored on the seabed? Then, in Shipwreck, Zac is searching underwater for a missing GIB agent. Can Zac find him in the mysterious Black Triangle before it's too late?