▁formation ▁of ▁the ▁G uns ling er , ▁from ▁a ▁normal ▁hum ano id ▁body . ▁It ▁also ▁has ▁an ▁explanation ▁of ▁the ▁making ▁of ▁the ▁G uns ling er ▁in ▁voice - over ▁by ▁K ah ler - J ex . ▁ ▁Syn opsis ▁The ▁Ele vent h ▁Doctor , ▁Amy ▁and ▁R ory ▁arrive ▁at ▁the ▁American ▁Front ier ▁town ▁of ▁Mer cy . ▁They ▁find ▁that ▁no ▁one ▁has ▁been ▁able ▁to ▁leave ▁or ▁enter ▁town ▁due ▁to ▁actions ▁of ▁" The ▁G uns ling er ", ▁who ▁dem ands ▁they ▁turn ▁over ▁K ah ler - J ex , ▁an ▁al ien ▁scient ist ▁that ▁crash ed ▁to ▁Earth ▁years ▁earlier . ▁The ▁town spe ople ▁res cu ed ▁him , ▁and ▁in ▁exchange , ▁he ▁provided ▁them ▁with ▁primitive ▁electric ity ▁and ▁the ▁means ▁to ▁stop ▁a ▁ch ol era ▁out break . ▁The ▁town ' s ▁mar shal , ▁Isaac , ▁is ▁hes it ant ▁of ▁turning ▁over ▁his ▁friend ▁to ▁the ▁G uns ling er , ▁despite ▁being ▁near ▁the ▁end ▁of ▁their ▁supplies . ▁▁ ▁The ▁Doctor ▁s ne aks ▁out ▁to ▁get ▁the ▁T ARD IS ▁but ▁finds ▁J ex ' s ▁crash ed ▁ship ▁and ▁disco vers ▁he ▁was ▁one ▁of ▁several ▁scient ists ▁that ▁did ▁in hum ane ▁experiments ▁to ▁create ▁cy borg s ▁on ▁their ▁war - t orn ▁home world . ▁The ▁G uns ling er ▁arriv es , ▁and ▁confir ms ▁the ▁Doctor ' s ▁theory ▁that ▁he ▁is