have a tiger by the tail
have a wolf by the ear
hold a wolf by the ear

Elin Nordegren: Had Tiger by the tail.

Classic stories involving other dimensions include Robert A. Heinlein's -And He Built a Crooked House (1941), in which a California architect designs a house based on a three-dimensional projection of a tesseract; and Alan E. Nourse's Tiger by the Tail and The Universe Between (both 1951).