One of the most suspenseful stories I have read of is the book "The circus of adventure" by Enid Blyton. The main characters of the story are 5 children. Jack and Lucy - Ann are siblings who are adopted into the same family as Philip and Dinah (siblings as well). The last child is a most peculiar guest that would later be revealed to be a prince of Tauri-Hessia ( This is a fictitious country, mind you). The most suspenseful part was when after all of the children except for Jack were caught because of some complications in Tauri-Hessia (The reason why the prince was around in the first place). The first suspenseful part was when Jack and his parrot Kiki managed to get to Tauri-Hessia without the people knowing.
The second part was when in Tauri-Hessia, Jack found the rest and rescued them with the circus folk he was with. The scene is as shown in the picture below. The circus folk devised a plan to walk on the tightrope (They were tightrope walkers) then pull the children over a pulley. But if you don't read the whole book it is pretty hard for you to understand what I am saying.