The Introduction sets the scene: this book is a resource for adventures where the Doctor goes back in time rather than forwards, in particular when he goes way, way back to times when dinosaurs ruled the Earth. It also, slightly incongruosly, has a complete set of rules for spaceships including combat and chases, and an impressive array of ones you might encouter in your travels. Top that off with material on the Silurians themselves and an adventure, and there's plenty to get your teeth into.
The first chapter, History Repeating Itself, looks at what happens when your time travels take you back before human beings even existed. It talks about finding out precisely when you are, about how to survive and live off the land if for some reason you end up stuck there without your TARDIS. There's a sweep through different epochs of time with notes on how to distinguish them with a knowing glance at the fauna and flora, as well as details of possible adventures. Here having the various Doctor Sourcebooks comes in handy, as events are cross-referenced to where they were mentioned under the appropriate Doctor's adventures along with other ideas for you to develop for yourself if you fancy them. Information on extinction events and low-tech companions provide added material... and that's before you get to a whole bunch of story hooks and plot seeds! This section also includes ideas for when dinosaurs travel forwards in time and invade the present day. There's also a bestiary of dinosaurs, complete with stat blocks, so when dinosaurs do turn up, you'll know how they work. Illustrations include a very life-like triceratops, although the other dinosaur images are rather disappointing.
The next chapter is The Silurians and here we get the lowdown on this fascinating species. Strictly speaking they are not aliens. They lived on Earth - and sought refuge in hibernation when they thought it was going to be destroyed - long before humans were around. People going far enough back in time might meet them, and the hibernating ones wake up every so often too. There's loads of information about them here, starting off with the fact that there's no such thing as 'a Silurian' - there are two related species, quite distinct one from another... and each with several sub-species. There's information on their government and politics, how they lived in their hey-day and what happens when hibernating ones awaken. Notes cover the Doctor's previous encounters with Silurians, and there's a sample Silurian city should you fancy awakening some of them yourself. There are also sample Silurians and details of Silurian space arks and other technology. The chapter ends with some plot hooks and story seeds and notable Silurian individuals who've turned up before... and if one if the group fancies playing a Silurian, the information you'll need is here too.
Then comes a chapter titled Spaceships, which presents rules for spacehips and their operation, and for combat and chases involving them. There's also a veritable spotter's guide to just some of the myriad hordes of ships owned and operated by various spacefaring species. There are plenty of adventure seeds to get you going as well.
Finally, Asteroid Day is an adventure that involves loads of time travel, backwards and forwards, with Silurians attempting to survive a massive asteroid impact any way they can, UNIT worrying about some time travellers who have gone missing, and the Doctor and his companions stuck in the middle trying to sort it all out as problems pile upon problems. High stakes, high jinks, and all jolly good fun!
Overall, a fascinating if disjointed book - it's as if several ideas collided and got stuffed between the same set of covers. Yet it's all good material and provides serveal ways to enhance your game in interesting and novel directions. After all, spaceships and dinosaurs?