There are interesting details not in Leeson's narrative. But you can't fault the writers for not doing their homework and thoroughly laying out the context of the story and the cast of characters at Barings. After the opening section, Leeson isn't brought back into the narrative until well past the halfway point of the text. This is as much a history of Barings Bank as the story of its demise. There's really more detailed Barings history here than is maybe necessary.
The opening section begins at the end, recounting how bank officials, chasing down discrepancies and cash flow issues, finally unravel the catastrophic truth of what Leeson had been up to.
This book contains a great deal of detail involving the other people and history of the bank. But in any case Leeson was limited to his own point of view. Leeson's book is a great read, though it's debatable to what degree it may be self-serving and accurate. I've read Leeson's own book a few times but this is a 3rd party account written shortly after the events by a couple of Financial Times journalists named Gapper and Denton. This is an account of the collapse of Barings Bank in the 1990s due to rogue trader Nick Leeson.