In her wry opening scene -- a conspicuously unspectacular protest march undertaken to protect the ""Wild End"" of a public park from a proposed cycle track -- Janet McNeill characterizes with economy and verve each of the several children involved, the park that plays a leading role in their story, and their wider social background as well. And before we've quite lost interest in the fizzled march we're caught off guard with Ned, one of the participants and the last to leave the area, who is suddenly seized from behind by a larger boy rudely demanding food. Soon all six marchers are conspiring to feed and protect the ungrateful stranger -- ""aid and abet"" he calls it when anyone threatens to report him -- so that there's no question of turning back even after they discover that he's not as they first believed the runaway orphan who'd been described on the telly. The mysterious prisoner turns out to be just bad enough to avoid disappointing the reader, and before he is safely out of the park and temporarily out of trouble Ned's relationship with him, with the other children, and with his own uncommon Gram have undergone some subtle but sharply defined shifts. Illuminated throughout by Miss McNeill's glancing observations of the children's momentary thoughts and feelings, which are never expected but always exactly how such a child would react in the situation, the whole adventure is brisk and bright and roundly satisfying.