Marius' enchantment, great as it was, could not efface from his mind other pre-occupations.
While the wedding was in preparation, and while awaiting the date fixed upon, he caused difficult and scrupulous retrospective researches to be made.
He owed gratitude in various quarters; he owed it on his father's account, he owed it on his own.
There was Thenardier; there was the unknown man who had brought him, Marius, back to M. Gillenormand.
Marius endeavored to find these two men, not intending to marry, to be happy, and to forget them, and fearing that, were these debts of gratitude not discharged, they would leave a shadow on his life, which promised so brightly for the future.
It was impossible for him to leave all these arrears of suffering behind him, and he wished, before entering joyously into the future, to obtain a quittance from the past.
That Thenardier was a villain detracted nothing from the fact that he had saved Colonel Pontmercy. Thenardier was a ruffian in the eyes of all the world except Marius.
And Marius, ignorant of the real scene in the battle field of Waterloo, was not aware of the peculiar detail, that his father, so far as Thenardier was concerned was in the strange position of being indebted to the latter for his life, without being indebted to him for any gratitude.
None of the various agents whom Marius employed succeeded in discovering any trace of Thenardier. Obliteration appeared to be complete in that quarter. Madame Thenardier had died in prison pending the trial. Thenardier and his daughter Azelma, the only two remaining of that lamentable group, had plunged back into the gloom. The gulf of the social unknown had silently closed above those beings. On the surface there was not visible so much as that quiver, that trembling, those obscure concentric circles which announce that something has fallen in, and that the plummet may be dropped.
Madame Thenardier being dead, Boulatruelle being eliminated from the case, Claquesous having disappeared, the principal persons accused having escaped from prison, the trial connected with the ambush in the Gorbeau house had come to nothing.
That affair had remained rather obscure. The bench of Assizes had been obliged to content themselves with two subordinates. Panchaud, alias Printanier, alias Bigrenaille, and Demi-Liard, alias Deux-Milliards, who had been inconsistently condemned, after a hearing of both sides of the case, to ten years in the galleys. Hard labor for life had been the sentence pronounced against the escaped and contumacious accomplices.
Thenardier, the head and leader, had been, through contumacy, likewise condemned to death.
This sentence was the only information remaining about Thenardier, casting upon that buried name its sinister light like a candle beside a bier.
Moreover, by thrusting Thenardier back into the very remotest depths, through a fear of being re-captured, this sentence added to the density of the shadows which enveloped this man.
As for the other person, as for the unknown man who had saved Marius, the researches were at first to some extent successful, then came to an abrupt conclusion. They succeeded in finding the carriage which had brought Marius to the Rue des Filles-du-Calvaire on the evening of the 6th of June.
The coachman declared that, on the 6th of June, in obedience to the commands of a police-agent, he had stood from three o'clock in the afternoon until nightfall on the Quai des Champs-Elysees, above the outlet of the Grand Sewer; that, towards nine o'clock in the evening, the grating of the sewer, which abuts on the bank of the river, had opened; that a man had emerged therefrom, bearing on his shoulders another man, who seemed to be dead; that the agent, who was on the watch at that point, had arrested the living man and had seized the dead man; that, at the order of the police-agent, he, the coachman, had taken "all those folks" into his carriage; that they had first driven to the Rue des Filles-du-Calvaire; that they had there deposited the dead man; that the dead man was Monsieur Marius, and that he, the coachman, recognized him perfectly, although he was alive "this time"; that afterwards, they had entered the vehicle again, that he had whipped up his horses; a few paces from the gate of the Archives, they had called to him to halt; that there, in the street,they had paid him and left him, and that the police-agent had led the other man away; that he knew nothing more; that the night had been very dark.
Marius, as we have said, recalled nothing. He only remembered that he had been seized from behind by an energetic hand at the moment when he was falling backwards into the barricade; then, everything vanished so far as he was concerned.
He had only regained consciousness at M. Gillenormand's.
He was lost in conjectures.
He could not doubt his own identity. Still, how had it come to pass that, having fallen in the Rue de la Chanvrerie, he had been picked up by the police-agent on the banks of the Seine, near the Pont des Invalides?
Some one had carried him from the Quartier des Halles to the Champs-Elysees. And how? Through the sewer. Unheard-of devotion!
Some one? Who?
This was the man for whom Marius was searching.
Of this man, who was his savior, nothing; not a trace; not the faintest indication.
Marius, although forced to preserve great reserve, in that direction, pushed his inquiries as far as the prefecture of police. There, no more than elsewhere, did the information obtained lead to any enlightenment.
The prefecture knew less about the matter than did the hackney-coachman. They had no knowledge of any arrest having been made on the 6th of June at the mouth of the Grand Sewer.
No report of any agent had been received there upon this matter, which was regarded at the prefecture as a fable. The invention of this fable was attributed to the coachman.
A coachman who wants a gratuity is capable of anything, even of imagination. The fact was assured, nevertheless, and Marius could not doubt it, unless he doubted his own identity, as we have just said.
Everything about this singular enigma was inexplicable.
What had become of that man, that mysterious man, whom the coachman had seen emerge from the grating of the Grand Sewer bearing upon his back the unconscious Marius, and whom the police-agent on the watch had arrested in the very act of rescuing an insurgent? What had become of the agent himself?
Why had this agent preserved silence? Had the man succeeded in making his escape? Had he bribed the agent? Why did this man give no sign of life to Marius, who owed everything to him? His disinterestedness was no less tremendous than his devotion. Why had not that man appeared again? Perhaps he was above compensation, but no one is above gratitude. Was he dead? Who was the man? What sort of a face had he? No one could tell him this.
The coachman answered: "The night was very dark." Basque and Nicolette, all in a flutter, had looked only at their young master all covered with blood.
The porter, whose candle had lighted the tragic arrival of Marius, had been the only one to take note of the man in question, and this is the description that he gave:
"That man was terrible."
Marius had the blood-stained clothing which he had worn when he had been brought back to his grandfather preserved, in the hope that it would prove of service in his researches.
On examining the coat, it was found that one skirt had been torn in a singular way. A piece was missing.
One evening, Marius was speaking in the presence of Cosette and Jean Valjean of the whole of that singular adventure, of the innumerable inquiries which he had made, and of the fruitlessness of his efforts. The cold countenance of "Monsieur Fauchelevent" angered him.
He exclaimed, with a vivacity which had something of wrath in it:
"Yes, that man, whoever he may have been, was sublime. Do you know what he did, sir? He intervened like an archangel. He must have flung himself into the midst of the battle, have stolen me away, have opened the sewer, have dragged me into it and have carried me through it! He must have traversed more than a league and a half in those frightful subterranean galleries, bent over, weighed down, in the dark, in the cess-pool,--more than a league and a half, sir, with a corpse upon his back! And with what object? With the sole object of saving the corpse. And that corpse I was. He said to himself:There may still be a glimpse of life there, perchance; I will risk my own existence for that miserable spark!' And his existence he risked not once but twenty times! And every step was a danger. The proof of it is, that on emerging from the sewer, he was arrested. Do you know, sir, that that man did all this? And he had no recompense to expect. What was I? An insurgent. What was I? One of the conquered. Oh!if Cosette's six hundred thousand francs were mine . . ."
"They are yours," interrupted Jean Valjean.
"Well," resumed Marius, "I would give them all to find that man once more."
Jean Valjean remained silent.
狂欢的日子虽然使人销魂，但一点也不能抹去马吕斯思想中的其他挂虑。
婚礼正在准备，在等待佳期来临的时候，他设法在对往事作艰苦而又审慎的调查。
在多方面他都应当感恩，他为他的父亲感恩，也为自己报德。
一个是德纳第，还有那个把他马吕斯送回吉诺曼先生家中的陌生人。
马吕斯坚决要找到这两个人，他不愿意自己结婚过着幸福的日子而把他们遗忘，他并担心不把欠下的恩情偿还，会在他这从此将是光辉灿烂的生活中投下阴影。他不愿在他后面欠着未偿的债务，他要在愉快地进入未来生活之前，对过去有一张清账的收据。
德纳第尽管是个恶棍，但不等于池没有拯救过彭眉胥上校。所有的人，除了马吕斯之外，都认为德纳第是个匪徒。
马吕斯不了解当时滑铁卢战场上的真实情况，不知道这样一个特点：他的父亲处在这样一种奇特的境遇中，德纳第是他父亲的救命人，而不是恩人。
马吕斯所任用的各种侦察人员没有一个找得到德纳第的踪迹。似乎和这方面有关的情况已经全部消失了。德纳第的女人在预审时就已死在狱中，德纳第和他的女儿阿兹玛，这凄惨的一伙中仅存的两个人，也已潜入黑暗中。社会上那条不可知的深渊静静地将他们淹没了。水面上见不到一点颤动，一点战栗，也见不到那阴暗的圆形水纹，说明有东西掉在里面，人们可以进行探测。
德纳第的女人死了，蒲辣秃柳儿与本案无关，铁牙失踪了，主要的被告已逃出监狱，戈尔博破屋的绑架案等于流了产。案情仍不清楚，刑事法庭只抓住两个胁从犯：邦灼，又叫春天，又叫比格纳耶；还有半文钱，又叫二十亿，他们被审讯并判处十年苦役。在逃没有到案的同谋则被判处终身苦役。主犯德纳第，也被缺席判了死刑。这一判决是惟一留下来的和德纳第有关的事。在殓尸布裹着的名字上，投下了一道阴森的光，就象灵柩旁的一支蜡烛。
而且，为了害怕再被捕，德纳第被撵到了暗洞的最深处，这个判决使此人埋到深深的黑暗中。
至于另外一个，就是那个救了马吕斯的陌生人，开始寻找时有了点眉目，后来又停止不前了。人们设法找到了六月六日傍晚那辆把马吕斯送到受难修女街的街车。车夫说，六月六日，一个警察命令他“停在”爱丽舍广场的河岸旁、大阴沟的出口处，从下午三时等到傍晚；晚上九时左右，对着河岸的阴沟铁栅栏门开了，一个背着象是死人的汉子从那里走出来，警察正等候着，他逮捕了活人，抓住了死人。在警察的命令下，他，车夫，让“这一伙人”都坐上了他的马车，先到了受难修女街，把死人放下，他说死人就是马吕斯先生，他认得出他，虽然他“这一次”是活的；后来他们又坐上了马车，他还用鞭子赶着马到了离历史文物陈列馆门口不远的地方，叫他停车，在大街上付清车钱，他们便离去了，警察带走了那个人；此外他就一无所知；那时天已经很黑了。
马吕斯，我们已经说过，什么也回忆不起来。他只记得当他在街垒中向后倒下去时，一只强有力的手从后面抓住了他；
他后来不省人事。他到了吉诺曼先生家中方苏醒过来。
他百般推测但得不到解答。
他不能怀疑他自己本人。然而他明明倒在麻厂街，怎么又被警察在塞纳河滩残废军人院桥附近扶起来？是有人把他从菜市场区背到爱丽舍广场来的，怎么背来的？通过下水道。这真是前所未闻的忠忱献身！
有人？什么人？
马吕斯寻找的就是这个人。
关于这个人，他的救命人，没有消息，毫无迹象，连一点征兆也没有。
虽然马吕斯在这方面必须十分审慎，但他已把他的追查扩大到警署去了。可在那儿也和在别处一样，调查的结果并没有解决丝毫问题。警署没有马车夫了解得多，他们一点也不知道六月六日在大下水道铁栅栏那儿逮捕过人，他们没有得到警察方面任何与这方面有关的报告，警署认为这一切纯属编造，是马车夫造的谣。通常一个车夫为了得到一点小费，什么事都干得出来，甚至会去捏造。然而事情是实实在在的，马吕斯无法怀疑，除非怀疑他自己本人，这我们刚刚已经说过了。
所有的一切，在这个离奇的哑谜中，是无法解释的。
这个人，这个神秘的人，马车夫看见他背着昏过去的马吕斯从大下水道的铁栅栏门那里出来，埋伏着的警察当场抓住他在救一个暴动者，他后来怎样了？警察又上哪儿去了？那人是否已经逃跑？为什么这警察要保持缄默？警察受他的贿赂了吗？为什么这个人，马吕斯的救命人，一点不向马吕斯表示他还活在人间呢？这种大公无私的态度和慷慨献身的精神是同样奇伟的。为什么这个人不再露面了呢？可能他不愿要任何酬劳，但没有人不愿接受别人的感激的。他是否已经死去？他是怎样的一个人呢？他的面貌是什么样的？任何人也答不上来。马车夫回答说：“那天晚上天太黑了。”巴斯克和妮珂莱特魂不附体，当时只注意血流满面的年轻的主人。惟独门房，当他用蜡烛照着悲惨的马吕斯来到时，注意到了这个人，下面是他提供的特征：“这个人的神态令人感到恐怖。”
马吕斯把他带回外祖父家时穿的血迹斑斑的衣服保留着，希望能对他的搜索有用，当他仔细看着这件衣服时，发现下摆的一边很古怪地被人撕破了，而且还少了一块。
有一天晚上，马吕斯在珂赛特和冉阿让面前谈起了这桩离奇的遭遇以及他进行的无数得不到结果的查询。“割风先生”冷淡的表情使他很不耐烦。他很激动，几乎发怒似的喊道：
“是的，这个人，不论他是个怎样的人，他做的事真了不起。你知道他做了什么吗，先生？他好象一个大天使那样出现了，他在战火中把我偷出来，打开下水道，把我拖进去，背着我！在这可怕的长廊里弯着腰，屈着膝，在黑暗中，污水中，走了差不多一法里半，先生，背上还要背着一个死尸呢！他的目的何在？只是为了搭救这个死尸。而这个死尸就是我。他对自己说：‘可能还有一线生机，为了这可怜的一线生机，我会冒着生命危险！’而他不只冒了一次生命危险，而是二十次！他的每一步都很危险。证明就是他一出阴沟就被捕了。先生，这人所做的这一切您知道吗？他并不指望任何报酬。我当时是什么人？一个起义者。什么样的人呢？一个败兵。呵！如果珂赛特的六十万法郎是我的……”
“这钱是您的。”冉阿让插了一句。
“那么，”马吕斯接着说，“为了找到这个人，我宁愿花去这笔钱！”
对此冉阿让默不作声。