 The whale speaks to Cassie through song, telling her about a strange place of grass and trees under the ocean.Cassie has a feeling that this place is of Andalite origin, and the Animorphs wonder if Cassie's and Tobias's visions are a sort of distress call from an Andalite trapped in the ocean.They decide that the distress call is connected to the morphing ability, and Cassie and Tobias feel it the strongest because Cassie is the most in control of her morphing ability and Tobias is trapped in a morph.