I was taken by Dark Echo right from the very first page. It was unputdownable.
The story was told from the perspective of Martin Stannard. He accompanied his father, Magnus to buy a boat for his retirement plan. The boat was the famous Dark Echo, once belonged to Harry Spalding. It didn't take long though before they noticed there was more to the boat. There were the unexplained accidents that befell the workers who tried to restore the boat, its enigmatic first owner, and the boat's own mysterious past. All in all, these provided a good chilly build up for the story.
Cottam also blending in few historical figures such as Mick Collins, Harry Boland (who were portrayed in ways that made me want to learn more about them), and mentioned few others such as Bricktop, F. Scott Fitzgerald, Ernest Hemingway etc. for the effect of the 1920s. The First World War also had a major part in explaining the connections and solving the ultimate mystery of the dark force. In fact, the prologue took place during WWI.
The book introduced various characters; and they each had a distinctive voice. My favorite characters were Suzanne, Martin's girlfriend and Jayne Boyte. I liked Suzanne right from her first appearance. We saw further of her character development when the story was switch from Martin's first person of view to Suzanne in third in person. She was smart, intelligent, resourceful and I found to be admirable. Her love for Martin and her not giving up the fight in order to save him and his father made her much more likable to me. I enjoyed reading from her perspective more than that of Martin's. As for Jayne Boyte, she was a fun and remarkable woman for her era. And maybe in a way, she was reincarnated as Suzanne.
The few things I didn't like was one, I thought the story was a bit dragging prior to the voyage; two, the ending was disappointing. After the sinister build up, I expected more or at least a twisty dark ending. Three, there was one instance where Martin mentioned something that seemed important at the beginning, but then it was never brought up again. So, that was a little meh.