go　to　Hampstead。〃　　　　　Valentin　produced　his　official　card　and　said　very　rapidly：　〃Call　up　two　of　your　men　to　come　with　me　in　pursuit；〃　and　crossed　the　road　with　such　contagious　energy　that　the　ponderous　policeman　was　moved　to　almost　agile　obedience。　　In　a　minute　and　a　half　the　French　detective　was　joined　on　the　opposite　pavement　by　an　inspector　and　a　man　in　plain　clothes。　　　　　〃Well；　sir；〃　began　the　former；　with　smiling　importance；　〃and　what　may？〃　　　　　Valentin　pointed　suddenly　with　his　cane。　　〃I'll　tell　you　on　the　top　of　that　omnibus；〃　he　said；　and　was　darting　and　dodging　across　the　tangle　of　the　traffic。　　When　all　three　sank　panting　on　the　top　seats　of　the　yellow　vehicle；　the　inspector　said：　〃We　could　go　four　times　as　quick　in　a　taxi。〃　　　　　〃Quite　true；〃　replied　their　leader　placidly；　〃if　we　only　had　an　idea　of　where　we　were　going。〃　　　　　〃Well；　where　are　you　going？〃　asked　the　other；　staring。　　　　　Valentin　smoked　frowningly　for　a　few　seconds；　then；　removing　his　cigarette；　he　said：　〃If　you　know　what　a　man's　doing；　get　in　front　of　him；　but　if　you　want　to　guess　what　he's　doing；　keep　behind　him。　　Stray　when　he　strays；　stop　when　he　stops；　travel　as　slowly　as　he。　　Then　you　may　see　what　he　saw　and　may　act　as　he　acted。　　All　we　can　do　is　to　keep　our　eyes　skinned　for　a　queer　thing。〃　　　　　〃What　sort　of　queer　thing　do　you　mean？〃　asked　the　inspector。　　　　　〃Any　sort　of　queer　thing；〃　answered　Valentin；　and　relapsed　into　obstinate　silence。　　　　　The　yellow　omnibus　crawled　up　the　northern　roads　for　what　seemed　like　hours　on　end；　the　great　detective　would　not　explain　further；　and　perhaps　his　assistants　felt　a　silent　and　growing　doubt　of　his　errand。　　Perhaps；　also；　they　felt　a　silent　and　growing　desire　for　lunch；　for　the　hours　crept　long　past　the　normal　luncheon　hour；　and　the　long　roads　of　the　North　London　suburbs　seemed　to　shoot　out　into　length　after　length　like　an　infernal　telescope。　　It　was　one　of　those　journeys　on　which　a　man　perpetually　feels　that　now　at　last　he　must　have　come　to　the　end　of　the　universe；　and　then　finds　he　has　only　come　to　the　beginning　of　Tufnell　Park。　　London　died　away　in　draggled　taverns　and　dreary　scrubs；　and　then　was　unaccountably　born　again　in　blazing　high　streets　and　blatant　hotels。　　It　was　like　passing　through　thirteen　separate　vulgar　cities　all　just　touching　each　other。　　But　though　the　winter　twilight　was　already　threatening　the　road　ahead　of　them；　the　Parisian　detective　still　sat　silent　and　watchful；　eyeing　the　frontage　of　the　streets　that　slid　by　on　either　side。　　By　the　time　they　had　left　Camden　Town　behind；　the　policemen　were　nearly　asleep；　at　least；　they　gave　something　like　a　jump　as　Valentin　leapt　erect；　struck　a　hand　on　each　man's　shoulder；　and　shouted　to　the　driver　to　stop。　　　　　They　tumbled　down　the　steps　into　the　road　without　realising　why　they　had　been　dislodged；　when　they　looked　round　for　enlightenment　they　found　Valentin　triumphantly　pointing　his　finger　towards　a　window　on　the　left　side　of　the　road。　　It　was　a　large　window；　forming　part　of　the　long　facade　of　a　gilt　and　palatial　public…house；　it　was　the　part　reserved　for　respectable　dining；　and　labelled　〃Restaurant。〃　　This　window；　like　all　the　rest　along　the　frontage　of　the　hotel；　was　of　frosted　and　figured　glass；　but　in　the　middle　of　it　was　a　big；　black　smash；　like　a　star　in　the　ice。　　　　　〃Our　cue　at　last；〃　cried　Valentin；　waving　his　stick；　〃the　place　with　the　broken　window。〃　　　　　〃What　window？　　What　cue？〃　asked　his　principal　assistant。　〃Why；　what　proof　is　there　that　this　has　anything　to　do　with　them？〃　　　　　Valentin　almost　broke　his　bamboo　stick　with　rage。　　　　　〃Proof！〃　he　cried。　　〃Good　God！　the　man　is　looking　for　proof！　Why；　of　course；　the　chances　are　twenty　to　one　that　it　has　nothing　to　do　with　them。　　But　what　else　can　we　do？　　Don't　you　see　we　must　either　follow　one　wild　possibility　or　else　go　home　to　bed？〃　　He　banged　his　way　into　the　restaurant；　followed　by　his　companions；　and　they　were　soon　seated　at　a　late　luncheon　at　a　little　table；　and　looked　at　the　star　of　smashed　glass　from　the　inside。　　Not　that　it　was　very　informative　to　them　even　then。　　　　　〃Got　your　window　broken；　I　see；〃　said　Valentin　to　the　waiter　as　he　paid　the　bill。　　　　　〃Yes；　sir；〃　answered　the　attendant；　bending　busily　over　the　change；　to　which　Valentin　silently　added　an　enormous　tip。　　The　waiter　straightened　himself　with　mild　but　unmistakable　animation。　　　　　〃Ah；　yes；　sir；〃　he　said。　　〃Very　odd　thing；　that；　sir。〃　　　　　〃Indeed？〃　Tell　us　about　it；〃　said　the　detective　with　careless　curiosity。　　　　　〃Well；　two　gents　in　black　came　in；〃　said　the　waiter；　〃two　of　those　foreign　parsons　that　are　running　about。　　They　had　a　cheap　and　quiet　little　lunch；　and　one　of　them　paid　for　it　and　went　out。　The　other　was　just　going　out　to　join　him　when　I　looked　at　my　change　again　and　found　he'd　paid　me　more　than　three　times　too　much。　　‘Here；'　I　says　to　the　chap　who　was　nearly　out　of　the　door；　‘you've　paid　too　much。'　　‘Oh；'　he　says；　very　cool；　‘have　we？'　'Yes；'　I　says；　and　picks　up　the　bill　to　show　him。　　Well；　that　was　a　knock…out。〃　　　　　〃What　do　you　mean？〃　asked　his　interlocutor。　　　　　〃Well；　I'd　have　sworn　on　seven　Bibles　that　I'd　put　4s。　on　that　bill。　　But　now　I　saw　I'd　put　14s。；　as　plain　as　paint。〃　　　　　〃Well？〃　cried　Valentin；　moving　slowly；　but　with　burning　eyes；　〃and　then？〃　　　　　〃The　parson　at　the　door　he　says　all　serene；　‘Sorry　to　confuse　your　accounts；　but　it'll　pay　for　the　window。'　　‘What　window？'　I　says。　　‘The　one　I'm　going　to　break；'　he　says；　and　smashed　that　blessed　pane　with　his　umbrella。〃　　　　　All　three　inquirers　made　an　exclamation；　and　the　inspector　said　under　his　breath；　〃Are　we　after　escaped　lunatics？〃　　The　waiter　went　on　with　some　relish　for　the　ridiculous　story：　　　　　〃I　was　so　knocked　silly　for　a　second；　I　couldn't　do　anything。　The　man　marched　out　of　the　place　and　joined　his　friend　just　round　the　corner。　　Then　they　went　so　quick　up　Bullock　Street　that　I　couldn't　catch　them；　though　I　ran　round　the　bars　to　do　it。〃　　　　　〃Bullock　Street；〃　said　the　detective；　and　shot　up　that　thoroughfare　as　quickly　as　the　strange　couple　he　pursued。　　　　　Their　journey　now　took　them　through　bare　brick　ways　like　tunnels；　streets　with　few　lights　and　even　with　few　windows；　streets　that　seemed　built　out　of　the　blank　backs　of　everything　and　everywhere。　　Dusk　was　deepening；　and　it　was　not　easy　even　for　the　London　policemen　to　guess　in　what　exact　direction　they　were　treading。　　The　inspector；　however；　was　pretty　certain　that　they　would　eventually　strike　some　part　of　Hampstead　Heath。　　Abruptly　one　bulging　gas…lit　window　broke　the　blue　twilight　like　a　bull's…eye　lantern；　and　Valentin　stopped　an　instant　before　a　little　garish　sweetstuff　shop。　　After　an　instant's　hesitation　he　went　in；　he　stood　amid　the　gaudy　colours　of　the　confectionery　with　entire　gravity　and　bought　thirteen　chocolate　cigars　with　a　certain　care。　He　was　clearly　preparing　an　opening；　but　he　did　not　need　one。　　　　　An　angular；　elderly　young　woman　in　the　shop　had　regarded　his　elegant　appearance　with　a　merely　automatic　inquiry；　but　when　she　saw　the　door　behind　him　blocked　with　the　blue　uniform　of　the　inspector；　her　eyes　seemed　to　wake　up。　　　　　〃Oh；〃　she　said；　〃if　you've　come　about　that　parcel；　I've　sent　it　off　already。〃　　　　　〃Parcel？〃　repeated　Valentin；　and　it　was　his　turn　to　look　inquiring。　　　　　〃I　mean　the　parcel　the　gentleman　leftthe　clergyman　gentleman。〃　　　　　〃For　goodness'　sake；〃　said　Valentin；　leaning　forward　with　his　first　real　confession　of　eagerness；　〃for　Heaven's　sake　tell　us　what　happened　exactly。〃　　　　　〃Well；〃　said　the　woman　a　little　doubtfully；　〃the　clergymen　came　in　about　half　an　hour　ago　and　bought　some　peppermints　and　talked　a　bit；　and　then　went　off　towards　the　Heath。　　But　a　second　after；　one　of　them　runs　back　into　the　shop　and　says；　‘Have　I　left　a　parcel！'　　Well；　I　looked　everywhere　and　couldn't　see　one；　so　he　says；　‘Never　mind；　but　if　it　should　turn　up；　please　post　it　to　this　address；'　and　he　left　me　the　address　and　a　shilling　for　my　trouble。　　And　sure　enough；　though　I　thought　I'd　looked　everywhere；　I　found　he'd　left　a　brown　paper　parcel；　so　I　posted　it　to　the　place　he　said。　　I　can't　remember　the　address　now；　it　was　somewhere　in　Westminster。　　But　as　the　thing　seemed　so　important；　I　thought　perhaps　the　police　had　come　about　it。〃　　　　　〃So　they　have；〃　said　Valentin　shortly。　　〃Is　Hampstead　Heath　near　here？〃　　　　　〃Straight　on　for　fifteen　minutes；〃　said　the　woman；　〃and　you'll　come　right　out　on　the　open。〃　　Valentin　sprang　out　of　the　shop　and　began　to　run。　　The　other　detectives　followed　him　at　a　reluctant　trot。　　　　　The　street　they　threaded　was　so　narrow　and　shut　in　by　shadows　that　when　they　came　out　unexpectedly　into　the　void　common　and　vast　sky　they　were　startled　to　find　the　evening　still　so　light　and　clear。　　A　perfect　dome　of　peacock…green　sank　into　gold　amid　the　blackening　trees　and　the　dark　violet　distances。　　The　glowing　green　tint　was　just　deep　enough　to　pick　out　in　points　of　crystal　one　or　two　stars。　　All　that　was　left　of　the　daylight　lay　in　a　golden　glitter　across　the　edge　of　Hampstead　and　that　popular　hollow　which　is　called　the　Vale　of　Health。　　The　holiday　makers　who　roam　this　region　had　not　wholly　dispersed；　a　few　couples　sat　shapelessly　on　benches；　and　here　and　there　a　distant　girl　still　shrieked　in　one　of　the　swings。　　The　glory　of　heaven　deepened　and　darkened　around　the　sublime　vulgarity　of