What we hear about the universe can sometimes seem a bit unlikely, with most of it being in the form of unseen matter and energy. In On the Shores of the Unknown: A Short History of the Universe
Joseph Silk demonstrates that the evidence is stronger than you might think. He describes how the fluctuations in the Cosmological Microwave Background impose constraints on the nature of the cosmos, but goes on to look at several other discoveries which support the cosmologists models. In particular he examines what theories of galaxy formation can tell us about the large scale nature of universe.
Silk is an expert in the subject of cosmology, but this is a non-technical book - there is no mathematics in it, and you don't need to have studied physics to follow the arguments. However I wouldn't recommend it to someone who hasn't read any other books on cosmology as I feel that its rather rough-and-ready - the material isn't really presented in a way that could be followed easily by a complete beginner. On the other hand, if you have read several popular science books on cosmology, but are beginning wonder why we should give any more credence to professional cosmologists than to any other people's ideas, then this book will give you plenty of useful information.