▁crisis ▁in ▁Spring field ▁causes ▁the ▁sale ▁of ▁many ▁houses ▁and ▁release ▁of ▁all ▁low - level ▁crim inals ▁from ▁Spring field ▁Pen it enti ary , ▁including ▁a ▁man ▁named ▁W alt ▁Warren . ▁W alt ▁purch ases ▁a ▁house ▁next ▁door ▁to ▁the ▁Sim pson ▁family ▁and ▁char ms ▁the ▁neighborhood . ▁However , ▁Bart ▁is ▁convinced ▁that ▁W alt ▁is ▁S ides how ▁Bob ▁in ▁dis gu ise ▁because ▁they ▁have ▁the ▁same ▁voice . ▁He ▁tries ▁several ▁times ▁to ▁find ▁proof , ▁but ▁fails . ▁Mar ge ▁convin ces ▁him ▁otherwise ▁by ▁taking ▁him ▁to ▁the ▁pen it enti ary , ▁where ▁they ▁see ▁Bob ▁locked ▁in ▁a ▁p added ▁cell , ▁we aring ▁a ▁stra it jack et ▁and ▁writing ▁" B art ▁Sim pson ▁Will ▁Die !" ▁on ▁the ▁walls . ▁A ▁seem ingly ▁re ass ured ▁Bart ▁dec ides ▁to ▁go ▁to ▁a ▁baseball ▁game ▁with ▁W alt , ▁who ▁removes ▁his ▁small ▁sho es ▁to ▁show ▁his ▁long ▁feet ▁fol ded ▁inside , ▁reve aling ▁himself ▁to ▁be ▁S ides how ▁Bob . ▁Bob ▁rest ra ins ▁Bart ▁in ▁the ▁car ▁and ▁g ags ▁him ▁with ▁du ct ▁t ape , ▁planning ▁to ▁take ▁him ▁to ▁Five ▁Corn ers , ▁a ▁location ▁where ▁five ▁states ▁meet , ▁to ▁kill ▁him . ▁ ▁Meanwhile , ▁the ▁real ▁W alt ▁Warren ▁esc apes ▁prison ▁while ▁bearing ▁Bob ' s ▁hair ▁and ▁face ▁and ▁comes ▁to ▁the ▁Sim ps ons ' ▁home . ▁At ▁first , ▁everyone ▁thinks