Book four, written 30 years after the first three, had a rather abrupt ending, and unsatisfied questions - where is Earth? who was actively hiding it? how does it factor into history and the present day?

So book five was inevitable, and it does answer the above questions. Unfortunately, it does so with a meandering plot, openly fractious characters and somewhat tenuous connections to the rest of Isaac Asimov's books - most importantly the Robots series. One major character from those books makes an appearance at the very end of this book.

Like book four, this was told as one story instead of two, and now with only one point of view. What worked so well for me in the series early on was dropped. The only other mechanical complaint was that the book was quite long, meandering at times. Not only were openly hostile characters not fun to read, they were not fun for a lot of pages!

Next up would be some of the prequels, though I am in no rush to start them at this point. My advice for the Foundation series so far has to remain - read only the first three books.