Monster Blood

Evan Ross is twelve and stuck. His parents are house-hunting, so he is staying with his great-aunt Kathryn, an eccentric woman who is nearly deaf, and there is nothing to do. He and Andy, a neighbor his age, wander into an antique toy store and come out with a dusty can of Monster Blood.

The green goo looks like harmless fun. It is not. After Evan's cocker spaniel, Trigger, gets into it, the dog begins to grow, and the rest of the goo grows along with him.

There is no one to take the can back to, because the toy store has closed for good. Meanwhile the spreading mass heads toward a pair of bullying twins, though they are not the only ones in its way.

This is a children's horror story with a light, spooky tone. Scholastic first published it in 1992 as book three of R.L. Stine's original Goosebumps series. Newcomers can start here, and it began the Monster Blood sub-series of sequels.

As the goo gets bigger, suspicion settles on Aunt Kathryn's house, where something may be feeding it.