House Between the Worlds, hc, 1980

Fenton was only a 'tweenman, without body or shadow; his body lay back in the laboratory where Dr. Garnock was experimenting with a new drug. Yet Fenton was in the fiary world of the Alfar, helplessly watching the Faerie Queen of the Alfar attacked and captured by the hideous, goblinlike ironfolk. And he was fading, irresitibly being drawn back to his body. His only hope lay in finding the mysterious House between the Worlds. but the House could only be found when and where it wanted.