In Miss Nelson Is Missing, the titular blond teacher found it necessary to masquerade as witchlike substitute Viola Swamp in order to shape up her obstreperous class. Now, a few years later, Miss Nelson must take a week to have her tonsils out, and another goofy-looking class anticipates acting up . . . until a bigger kid who's been through it warns them of Miss Swamp. The stage thus set, they are relieved to get their principal Mr. Blandsworth as a sub; but after three days of his boring attempts to amuse them, the kids, as Allard puts it, hatch a plot. What follows is a marvelous complication of masquerades, with the kids impersonating Miss Nelson, Miss Nelson appearing as Miss Swamp, and Miss Nelson-as-Miss Swamp masquerading as Miss Nelson. A nifty performance, always a step or two ahead of the audience.