Spirited illustrations spark text, Simon's Book, by Henrik Drescher. New York: Lothrop, Lee & Shepard. 32 pp. $10. Ages 5-8.

This inventive book snaps with energy and scratchy pen-and-ink illustrations. Spirited and unconventional, it offers a refreshing change from sugarcoated children's fare.

The suspenseful story begins with a young boy who starts to draw a story about Simon and a furry beast, leaving it unfinished to go to bed. In the dark of night his pens creep out of their canister, snakelike, and onto the drawing pad, where Simon faces the long-nosed beast. They are joined by the ink bottle, which promptly douses Simon in black. Wasting no time, the beast leaps at the group, and a chase is on.

''The fastest pen drew a hole in the page. They thought it would be too small for the beast to follow through . . . BUT IT WASN'T.'' And the chase resumes in a frenzy over a rocky hill and through ink splatters. Finally, Simon is cornered. The beast pounces - and plants a big kiss on Simon's cheek.

Relieved, the new comrades arrive at the last page. The pens draw a warm bed, Simon and the beast are tucked in, and all return to their proper places.

In the morning, the young boy wakes up to find a book on his drawing table. The same book, in fact, you have been reading.