I was very hesitant to read this - the author’s Einstein book was painfully inaccurate - but I love Agatha Christie so I decided to give it a shot. 

Christie was actually involved in a real life mystery - she disappeared for 11 days after learning about her husband’s infidelity. For the rest of her life she never spoke about what happened to her while she was gone. Benedict has taken this event and  created an entertaining work of fiction, theorizing on what happened to her. It’s a very creative take on it, relying heavily on Christie’s talent for creating unsolvable mysteries. 

The reality was likely far less exciting, but the idea is still solid. You definitely need to suspend disbelief and try and enjoy it as the fiction it is.