Brent waved back and did the only thing possible. As he walked slowly forward he saw that Di Costa’s curiosity had gotten the better of him. Brent watched him open the note, read it--and change suddenly. The man’s arm dropped to his side, his body stiffened. Staring straight ahead, he stood on the walkway, eyes fixed and as full as a Roman portrait bust. * * * * * Dalgreen hurried toward the man. Events were going too fast. He had more than a suspicion that the note and the short man were somehow connected with the secret of the paintings. He stepped forward. The man stared ahead, unseeing and unhearing. Brent felt justified in removing the mysterious note from between his fingers. One side was blank, but the other contained a single illegible character--queer sign made up of flowing curves crossed by choppy green lines. It resembled nothing Brent had ever seen in his entire life. They rode uptown side by side. Brent leaned on the railing while Di Costa remained fixed in his strange trance. The note in Brent’s hand was tangible evidence that his suspicions had some basis in fact. As he examined it again, he was aware of an undefinable tingling in his hand. The note seemed to be vibrating, shaking free from his hand in some unknown way. Under his startled gaze it glowed suddenly and disappeared! One instant he had held it, the next his hand was empty. He leaped back in surprise--passing through the space formerly occupied by Di Costa. Gone--while he had been studying the note! Leaning over the rail he had a quick glimpse of the stiff figure entering the Central Park Skyport. Cursing himself for his stupidity, Brent changed lanes and raced back to the Skyport entrance. His luck still held. Di Costa was on the outgoing air cab line. It would take him at least ten minutes to get a cab this time of day. With a little speed and a few greased palms Brent could rent a Fly-Your-Own before the other man was airborne. Shortly after, the orange and black cab flashed up from the take-off circle followed closely by Brent’s blue helio. The two aircraft flew north and vanished in the distance over the Hudson. The air cab stayed at the 10,000 foot level. Brent cruised at 8,000, lagging slightly behind, keeping in the blind spot of the other ship. The entire affair was moving too fast for his peace of mind. He had the feeling that he was no longer a free agent, that he was being pushed into things before he decided for himself. * * * * * He suddenly felt elated. The strange symbol on the note, the note that disappeared in such an inexplicable fashion, _proved_ the existence of alien hidden forces. Every mile that rushed under his plane brought him closer to the answer. He didn’t fear death--it was no longer a stranger to him. The moments of time left to him might be made more satisfactory if he ferreted out this secret. He smiled to himself.