I'd urge caution about Hidden History - it's a bit of a conspiracy theorist rant by non-historians, and its central thesis (shadowy cabals of politicians and bankers plotted for decades to bring about the long-term destruction of Germany) isn't really supported by the evidence.
I'd encourage anyone interested to first read more than one of the works listed in order to better appreciate the various arguments - perhaps Max Hastings' Catastrophe 1914 as a very readable restatement of the mainstream position to contrast with Clark's Sleepwalkers - before approaching fringe material like Hidden History.
There are, inevitably, a wide range of views on the origins of WW1 - Wikipedia actually has a really good overview at https://en.wikipedia.org/wiki/Historiography_of_the_causes_o...
I'd encourage anyone interested to first read more than one of the works listed in order to better appreciate the various arguments - perhaps Max Hastings' Catastrophe 1914 as a very readable restatement of the mainstream position to contrast with Clark's Sleepwalkers - before approaching fringe material like Hidden History.