And one of the things they had in common, at that time, was a vague and mysterious fear of the old man called the Professor. (1.5)
The kids in the neighborhood are scared of the Professor, though they don't really know why. What's so scary about a mysterious old man who always keeps to himself and has a completely secret personal life? Oh right. All of that.
It occurred to all of them, though, that the rumors had been frightening enough to make Mrs. Ross cancel her after-school remedial reading class—which she almost never did—and come home early. And Melanie noticed a strangeness in her voice and that her hand shook as she put milk and cookies on the table. (8.9)
The fact that Mrs. Ross won't tell the kids what has happened makes this whole situation even scarier. What could have possibly happened to frighten all the adults in the neighborhood?
As the days passed and no arrests were made, fear and suspicion grew and spread in all directions; and a great silence began to settle over Orchard Avenue and the streets and alleys on either side. (8.12)
The news is pretty grim: someone has kidnapped and murdered a young girl in the neighborhood. Worse yet, the murderer hasn't been caught, which (rightly) puts everyone in the neighborhood on high alert.
From somewhere not too far away, perhaps the main alley behind the Casa Rosada, Mrs. Ross's voice was calling, "Melanie! Marshall! Melanie!" There was something about the tone of her voice that made Melanie's eyes widen with fear.
"Something's wrong," she said. (8.3-4)
Mrs. Ross is a pretty tough woman, so when Melanie and April hear her calling for them with real fear in her voice, they know that something's up. And like good little kids, they return home right away, even though it's kind of early to be called inside. Nothing like fear to shut down a good game.
"The gods demand that we make a horrible and bloody sacrifice." April took up Melanie's theme with relish. "A horrible and bloody sacrifice," Melanie agreed. "A horrible and bloody sacrifice," Marshall and Elizabeth repeated dutifully, but Elizabeth's voice quavered a little and Marshall leaned over and poked his sister. (11.6-8)
Elizabeth and Marshall go along with all of Melanie and April's Egyptian rituals, but that doesn't mean that they're not occasionally spooked by them. When April starts talking about a sacrifice, the two younger kids can't help focusing on the "horrible" and the "bloody" and wondering what happened to the make-believe.
More spooky and supernatural. Even though all the Egyptians were positive that somebody was fooling and had somehow managed to write the answer to Ken's question, there are times when being positive isn't quite enough. (17.33)
When the oracle answers Ken's question and no one fesses up to writing the response, everyone is a bit spooked. The Egypt Game was all about make-believe…what if it really does have its own magic?
She was holding the board open for Marshall when, out of the darkness and silence behind, something grabbed her with crushing strength, and big hard fingers smothered the scream that sprang into her throat. (20.31)
Now here's something that should really frighten April. Getting grabbed by the murderer in the middle of the night in an abandoned yard isn't exactly what she was planning. What will they do now? (The answer: wait until the Professor screams, then escape. In case you forgot and were suffering from the suspense.)
"He might be watching us through it, though." Somehow, that thought was almost more scary than the possibility of the Professor's actually entering the yard. With one accord the girls moved warily toward the window. (5.6-7)
The girls aren't necessarily afraid that the Professor will storm into the yard and kick them out. The prospect of him watching them play the Egypt Game secretly is way creepier. It's unsettling being watched, after all.
Later, when Melanie began to think about it in private, she began to have some doubts. Even though the Egypt gang had decided that the Professor was innocent, what if they just might be wrong? Or what if the Professor was innocent, but the somebody else who wasn't really did live right in the neighborhood, as so many people seemed to think? (9.6)
Although Melanie initially agrees with April's plan to sneak into Egypt on Halloween, the anxieties starting creeping up later on. After all, there is a murderer on the loose in the neighborhood.
When the shapeless inhuman figure sprang into the middle of the storage yard, the four Egyptians could only clutch at each other in panic, too shocked for the moment to even scream. (12.1)
Nothing boosts the imagination like a giant, ghostly shape bursting in unannounced. Especially when there's a murderer on the loose in town. Luckily for the kids, this time it turns out to just be Toby and Ken, the two jokers from school.