Trolley to Yesterday by John Bellairs

Did we, Fergie?"
    Fergie shook his head. Like Johnny he was not at all ashamed of what he had done. But he was scared.
    The professor was genuinely touched. His eyes filled with tears, but then he pulled himself together, harrumphed, and tried to look dignified. "Gentlemen," he said in a strained voice, "I... I don't quite know what to say. It was good of you to be concerned about me, but... well, you know what a reasonable, restrained person I am. I would never do anything that would endanger my life."
    Sure you wouldn't! thought Fergie, but he said nothing. Johnny began to glance nervously at the eerie, swirling mist.
    "Where are we?" he asked in an awestruck voice.
    "Where?" said the professor with a faint smile. "Well, out here you are between times, in the void, and if you step off this platform into the mist you won't be seen again, I promise you. But the trolley is hovering next to Leander's Tower, and once again we are ready to enter the long-lost world of 1453. By the way, in case you were wondering why I had my glasses off, I was trying to see if I could get along without them—they didn't have eyeglasses in the fifteenth century. Of course, I could use contact lenses, but I'm deathly afraid that I'll fall asleep with them on and suffer eye damage. I'm just running on, as usual: Come inside, and we can go out the side door as we did the other time. We won't stay long—just a couple of minutes."
    Fergie and Johnny followed the professor through the door into the lighted interior of the car. Immediately both of them stopped and stared at a large bundle that lay on the floor between the rows of seats. There was the rubber life raft, and stuck under the straps that bound it was the professor's Knights of Columbus sword. On top of the heap lay an old, scuffed, black leather valise.
    The professor's face got red. "I... I'll bet you're wondering what all this paraphernalia is for, aren't you?" he asked nervously.
    Fergie grinned. "No, prof, as a matter of fact, we weren't wondering! We saw you buy that raft downtown and we figured you were gettin' ready to make your move soon. We were gonna try and stop you—that's why we jumped on the trolley. You can't fool us—we can read you like a book!"
    The professor coughed and glanced hurriedly away. "Well?" he said brusquely. "What on earth did you expect me to do? Eh? I've been thinking about Constantinople night and day ever since I found this ridiculous Time Trolley, and I just couldn't give up if there's even a tiny chance that I could save those poor people in the church."
    Johnny's eyes grew wide "But professor!" he said in a puzzled tone. "What were you gonna do? I mean, you couldn't fight off the Turkish army all by yourself."
    The professor's face got redder. He folded his arms and stared at the floor. "If you must know," he said quietly, "I was going to pretend to be an Angel of Light. Remember the legend I told you about? The people of Constantinople believed that an angel would come down into the great Church of the Holy Wisdom and drive away the enemy, even if the city walls had been battered down and all hope seemed to be gone. I know I don't look much like an angel, but... well, let me show you."
    The professor bent down and undid the snaps on the black valise. He reached in and pulled out an odd-looking pistol. It had a stubby, tube-shaped barrel with a wide mouth. Johnny had seen guns like this in the movies, and he knew instantly that it was a flare pistol. Soldiers used them to signal their friends when they were in trouble. They fired the flares into the air, and the flares burst with a white or colored light, like Fourth of July skyrockets.
    "I have a box of white flares in the valise," said the professor as he turned the gun over in his hands. "Normally they're set to explode at a great height, but I have shortened the fuses on these, so they will explode inside the dome of the church where the people will be hiding. I got the height of the