As a big fan of Dan Brown's book this series was a complete disappointment. They had changed the entire story... it's no more Dan's The Lost Symbol. Relationships had been changed, the actual journey, emotions and sequence of the book everything was changed. I felt like the writer of this series could have actually read the book before cooking up this story.
There were so many breath taking sequences in the book which they failed to adapt.
In book, Malakh is actually killed and later on they will come to know it was Zach from his diary. And also the secret of the ancient knowledge and secret was revealed to Langdon.
In general, it was just a watchable series that it... you can watch it for killing time.
But I would still recommend the Book not the series...