Rose and Jack are brother and sister, but they are as unlike as possible. Rose is prim, quiet and fearful while Jack loves rough and tumble. He sometimes scares her at night because he knows she will be afraid. Their respective personalities are symbolised by the end papers in the book. Hers is a William Morris style design of flowers, and his is a solid brick wall. They argue constantly, and when mum finally sends them out, Jack is disgusted because Rose has to tag along. He wants to go adventuring and when he finds a tunnel, he slithers into it without hesitation. Rose is badly frightened, but realises she must go after him. She conquers her fears of the tunnel and the weird wood on the other side because she knows her brother is in trouble and needs her. It is fearful Rose who saves Jack, and they learn that they love each other after all. Outstanding illustrations as would be expected from this artist, and there are no gorillas!