While the Cat's Away is a novella written by Margot Batrae. It was first published in 1999 and is the twenty-fifth book in the Sabrina the Teenage Witch book series.
Description[]
"Natural Disaster!" When an inter-realm hurricane traps Drell on the wrong side of the linen closet, his powers are temporarily on the blitz. While he waits for them to return, Sabrina covers for him in exchange for a Heart's Desire chip. But when Salem swallows it and morphs into a human form, it's goodbye Mystery Meat Mix, hello teenage boy!
Now Sabrina must hide Salem until she figures out how to return him into his feline form. She takes him to the only place a teenage boy can go unnoticed -- high school. But the failed despot in Salem soon takes over the "school!"
Sabrina can't stand Salem like this. But can she turn him back before the inter-realm hurricane clears and Drell returns to the Other Realm?