▁under ▁the ▁est u ary . ▁The ▁Doctor ▁bel ieves ▁it ▁is ▁a ▁P es cat on ▁ship . ▁ ▁The ▁P es cat ons ▁are ▁c archar hin idae , ▁or ▁deep ▁water ▁sh arks . ▁The ▁exper ts ▁sc off ▁at ▁this , ▁until ▁one ▁comes ▁out ▁of ▁the ▁Th ames ▁and ▁makes ▁its ▁way ▁to ▁London ▁Z oo ▁in ▁search ▁of ▁salt ▁water . ▁The ▁Doctor ▁confront s ▁it ▁in ▁the ▁Aqu arium , ▁where ▁it ▁dies ▁and ▁dis integr ates . ▁ ▁That ▁night , ▁more ▁meteor ites ▁land ▁in ▁the ▁Th ames . ▁ ▁Part ▁ 2 ▁ ▁London ▁is ▁inv aded . ▁The ▁Doctor ▁rec alls ▁his ▁visit ▁to ▁planet ▁P es ca , ▁where ▁he ▁fell ▁down ▁a ▁ch asm ▁into ▁a ▁ca vern ▁and ▁met ▁Z or , ▁the ▁P es cat on ▁leader . ▁Z or ▁said ▁he ▁would ▁use ▁the ▁Doctor ▁to ▁find ▁a ▁new ▁home ; ▁P es ca ▁was ▁dry ing ▁out ▁and ▁falling ▁towards ▁its ▁sun . ▁Z or ▁used ▁his ▁hyp not ic ▁powers ▁on ▁the ▁Doctor , ▁who ▁fought ▁back ▁and ▁escaped . ▁Back ▁in ▁London , ▁Sarah ▁Jane ▁finds ▁an ▁abandoned ▁baby ▁while ▁the ▁military ▁shoot ▁r ounds ▁at ▁the ▁inv ading ▁P es cat ons ▁with ▁no ▁effect . ▁The ▁Doctor ▁dist ract s ▁a ▁P es cat on ▁by ▁singing ▁" Hello , ▁Dol ly !" ▁and ▁doing ▁a ▁dance ▁so ▁that ▁Sarah ▁Jane ▁can ▁get ▁away ▁with ▁the ▁child . ▁Finally ▁the ▁P es