Beyond Earth's Gate by Lewis Padgett

Seldom discussed, if at all, is "Beyond Earth's Gates," a novel that first saw the light of day in the September 1949 issue of "Startling Stories," under the title "The Portal in the Picture." In it, we meet Eddie Burton, an up-and-coming Broadway actor who gets into big trouble with the cops when his annoying ladyfriend, Lorna, disappears into a framed Rousseau painting on his living room wall! Shortly thereafter, Eddie also disappears into the portal in the picture, and appears in the land of Malesco, which he had heard about in supposedly make-believe stories told by his uncle many years before. Malesco, as it turns out, is all too real; a sort of alternate Earth that had split off from our own space/time shortly after the rule of Caligula. Vaguely Roman in setup, Malesco is completely dominated by its priesthood, the keepers of the religion of Alchemy, and lorded over by the very intimidating figure known as the Hierarch. As had Uncle Jim, Eddie and Lorna become involved in an incipient people's revolution against the priesthood; a seemingly hopeless cause....

To make their bizarre plot a bit more credible, the authors continuously have Eddie tell us that he is no hero. He makes constant references to Edgar Rice Burroughs and H. Rider Haggard, telling us that John Carter might do this or Allan Quatermain might do that, but that he was too chickenhearted to do anything. Eddie is certainly not your classic adventure hero; just a dude who's gotten in waaay over his head, and this somehow makes the story more believable.  When he learns that the Malescans look on N.Y.C. as an otherworldly paradise, he says, "Believe me, I know better!" This short novel concludes with an extremely suspenseful denouement, with Eddie facing off against the Hierarch whilst thousands of Malescans watch the fate of their world hang in the balance.  (s. ferber - Amazon)