BEYOND 'ECSTASY' "MDMA temporarily lowers interpersonal boundaries," said the Harvard doctor. "Hex dissolves them." "The potential for abuse, for mind control, is terrifying," said the Berkeley psychopharmacology professor. Outside, packs of painfully thin kids in hex-sign T-shirts--the "hexies"--quiver and murmur and make their telepathic suicide pacts. Someone is trying to destroy a generation. Sarah "Sunny" Randall wants to know who. The...