er ▁arriv es ▁the ▁next ▁day , ▁residents ▁we aring ▁fa cial ▁mark ings ▁similar ▁to ▁J ex ▁race ▁through ▁town , ▁confusing ▁the ▁cy borg ▁and ▁allowing ▁J ex ▁to ▁fle e ▁to ▁his ▁ship . ▁However , ▁instead ▁of ▁taking ▁off , ▁J ex ▁tells ▁the ▁Doctor ▁he ▁is ▁ready ▁to ▁face ▁justice ▁in ▁the ▁after life , ▁and ▁causes ▁the ▁ship ▁to ▁self - dest ruct . ▁ ▁The ▁G uns ling er ▁with ▁no ▁further ▁purpose ▁prepar es ▁to ▁travel ▁a ▁distance ▁to ▁self - dest ruct , ▁but ▁the ▁Doctor ▁suggests ▁a ▁new ▁resolve . ▁As ▁the ▁Doctor , ▁Amy ▁and ▁R ory ▁leave , ▁the ▁G uns ling er ▁stands ▁watch ▁over ▁Mer cy ▁as ▁its ▁new ▁mar shal . ▁ ▁Production ▁ ▁In ▁looking ▁to ▁give ▁each ▁episode ▁of ▁the ▁series ▁a ▁distinct ▁feel , ▁show runner ▁Steven ▁M off at ▁pitch ed ▁the ▁Wild ▁West ▁theme ▁to ▁writer ▁T oby ▁Wh ith ouse , ▁suggesting ▁that ▁the ▁episode ▁could ▁be ▁about ▁a ▁town ▁terror ised ▁by ▁a ▁robot . ▁M off at ▁was ▁keen ▁on ▁putting ▁Matt ▁Smith ▁in ▁a ▁Western ▁setting , ▁who ▁he ▁called ▁one ▁of ▁the ▁last ▁people ▁one ▁would ▁expect ▁to ▁replace ▁Cl int ▁East wood . ▁Wh ith ouse ▁had ▁previously ▁written ▁the ▁Doctor ▁Who ▁episodes ▁" Sch ool ▁Re union " ▁( 2 0 0 6 ), ▁" The ▁V amp ires ▁of ▁Ven ice " ▁( 2 0 1 0 ), ▁and ▁" The ▁God ▁Complex " ▁(