This seems a reasonable way to approach this tale, since the story itself is highly structured and visual – cinematic, even, in that simultaneous events ( and, indeed, the back-stories) are described with a singular economy without interrupting the flow of the story. The King James Bible version is here.
Tobit, a devout and righteous man of Nineveh, ruled by the Assyrians, has become blind and can no longer, as he did before, bury the dead of the city secretly at night in accordance with the precepts of his faith – an illegal act. Wishing to die, he remembers the money he has left in trust to Gabael at Rages in Media and resolves to send his son Tobias to reclaim his property before he dies. So, Tobias goes to the marketplace to find a hired companion for the journey and meets Azarias. And his dog….
Tobias receives his father’s blessing – William-Adolphe Bouguereau
And when his son had prepared all things far the journey, his father said, Go thou with this man, and God, which dwelleth in heaven, prosper your journey, and the angel of God keep you company. So they went forth both, and the young man’s dog with them.
Tobias and the Angel – Pietro Perugino
Meanwhile, over in Ecbatana, Raguel’s daughter Sarah is mourning, for she has had seven bridegrooms, each of which was slain by the demon Asmodeus on his wedding night. Azarias tells Tobias to kill a fish and to take it to Ecbatana, for the smoke of the heart and liver will rout a demon and the gall will cure his father’s sight. And Sarah, as a kinswoman of Tobias, is his proper and true bride.
Tobias and the Angel and the Fish – Gustave Dore
Fear not, O my brother; for she shall be given thee to wife; and make thou no reckoning of the evil spirit; for this same night shall she be given thee in marriage. And when thou shalt come into the marriage chamber, thou shalt take the ashes of perfume, and shalt lay upon them some of the heart and liver of the fish, and shalt make a smoke with it: And the devil shall smell it, and flee away, and never come again any more: but when thou shalt come to her, rise up both of you, and pray to God which is merciful, who will have pity on you, and save you: fear not, for she is appointed unto thee from the beginning; and thou shalt preserve her, and she shall go with thee. Moreover I suppose that she shall bear thee children. Now when Tobias had heard these things, he loved her, and his heart was effectually joined to her.
The Wedding of Sarah and Tobias – Jan Steen… the demon is disposed of…
 And when they had supped, they brought Tobias in unto her. And as he went, he remembered the words of Raphael, and took the ashes of the perfumes, and put the heart and the liver of the fish thereupon, and made a smoke therewith. The which smell when the evil spirit had smelled, he fled into the utmost parts of Egypt, and the angel bound him.  And after that they were both shut in together, Tobias rose out of the bed, and said, Sister, arise, and let us pray that God would have pity on us. Then began Tobias to say, Blessed art thou, O God of our fathers, and blessed is thy holy and glorious name for ever; let the heavens bless thee, and all thy creatures. Thou madest Adam, and gavest him Eve his wife for an helper and stay: of them came mankind: thou hast said, It is not good that man should be alone; let us make unto him an aid like unto himself. And now, O Lord, I take not this my sister for lust but uprightly: therefore mercifully ordain that we may become aged together. And she said with him, Amen.  So they slept both that night.
On finding the young couple alive in the morning, Raguel rejoices:
Then Raguel praised God, and said, O God, thou art worthy to be praised with all pure and holy praise; therefore let thy saints praise thee with all thy creatures; and let all thine angels and thine elect praise thee for ever.  Thou art to be praised, for thou hast made me joyful; and that is not come to me which I suspected; but thou hast dealt with us according to thy great mercy.  Thou art to be praised because thou hast had mercy of two that were the only begotten children of their fathers: grant them mercy, O Lord, and finish their life in health with joy and mercy.
And he bids his servants fill in the grave he has secretly dug for Tobias and then begins the fourteen-day wedding feast…..
The Wedding of Sarah and Tobias – Jan Steen
Meanwhile, back in Nineveh….Tobit and Anna his wife are awaiting their son’s return:
Tobit and Anna – Rembrandt
 Now Tobit his father counted every day: and when the days of the journey were expired, and they came not, Then Tobit said, Are they detained? or is Gabael dead, and there is no man to give him the money? Therefore he was very sorry. Then his wife said unto him, My son is dead, seeing he stayeth long; and she began to wail him, and said, Now I care for nothing, my son, since I have let thee go, the light of mine eyes. To whom Tobit said, Hold thy peace, take no care, for he is safe. But she said, Hold thy peace, and deceive me not; my son is dead. And she went out every day into the way which they went, and did eat no meat on the daytime, and ceased not whole nights to bewail her son Tobias, until the fourteen days of the wedding were expired, which Raguel had sworn that he should spend there. Then Tobias said to Raguel, Let me go, for my father and my mother look no more to see me.
He resists Raguel’s entreaties to stay and he and Azarias return home…
The Return of Tobias – Nikolai Ge
….So they went their way, and the dog went after them. Now Anna sat looking about toward the way for her son. And when she espied him coming, she said to his father, Behold, thy son cometh, and the man that went with him. Then said Raphael, I know, Tobias, that thy father will open his eyes.  Therefore anoint thou his eyes with the gall, and being pricked therewith, he shall rub, and the whiteness shall fall away, and he shall see thee. Then Anna ran forth, and fell upon the neck of her son, and said unto him, Seeing I have seen thee, my son, from henceforth I am content to die. And they wept both.
Tobias restores his father’s sight – Jan van Hemessen
 Tobit also went forth toward the door, and stumbled: but his son ran unto him,
 And took hold of his father: and he strake of the gall on his fathers’ eyes, saying, Be of good hope, my father. And when his eyes began to smart, he rubbed them;
 And the whiteness pilled away from the corners of his eyes: and when he saw his son, he fell upon his neck. And he wept, and said, Blessed art thou, O God, and blessed is thy name for ever; and blessed are all thine holy angels: For thou hast scourged, and hast taken pity on me: for, behold, I see my son Tobias. And his son went in rejoicing, and told his father the great things that had happened to him in Media. Then Tobit went out to meet his daughter in law at the gate of Nineve, rejoicing and praising God: and they which saw him go marvelled, because he had received his sight.
And Azarias reveals himself – although we have known all along who he really is:
 I am Raphael, one of the seven holy angels, which present the prayers of the saints, and which go in and out before the glory of the Holy One. Then they were both troubled, and fell upon their faces: for they feared. But he said unto them, Fear not, for it shall go well with you; praise God therefore. For not of any favour of mine, but by the will of our God I came; wherefore praise him for ever. All these days I did appear unto you; but I did neither eat nor drink, but ye did see a vision. Now therefore give God thanks: for I go up to him that sent me; but write all things which are done in a book. And when they arose, they saw him no more. Then they confessed the great and wonderful works of God, and how the angel of the Lord had appeared unto them.
The Angel departing from the family of Tobias – Rembrandt
 Then Tobit wrote a prayer of rejoicing, and said, Blessed be God that liveth for ever, and blessed be his kingdom.  For he doth scourge, and hath mercy: he leadeth down to hell, and bringeth up again: neither is there any that can avoid his hand. Confess him before the Gentiles, ye children of Israel: for he hath scattered us among them. There declare his greatness, and extol him before all the living: for he is our Lord, and he is the God our Father for ever. And he will scourge us for our iniquities, and will have mercy again, and will gather us out of all nations, among whom he hath scattered us. If ye turn to him with your whole heart, and with your whole mind, and deal uprightly before him, then will he turn unto you, and will not hide his face from you. Therefore see what he will do with you, and confess him with your whole mouth, and praise the Lord of might, and extol the everlasting King. In the land of my captivity do I praise him, and declare his might and majesty to a sinful nation. O ye sinners, turn and do justice before him: who can tell if he will accept you, and have mercy on you? I will extol my God, and my soul shall praise the King of heaven, and shall rejoice in his greatness. Let all men speak, and let all praise him for his righteousness. O Jerusalem, the holy city, he will scourge thee for thy children’s works, and will have mercy again on the sons of the righteous. Give praise to the Lord, for he is good: and praise the everlasting King, that his tabernacle may be builded in thee again with joy, and let him make joyful there in thee those that are captives, and love in thee for ever those that are miserable. Many nations shall come from far to the name of the Lord God with gifts in their hands, even gifts to the King of heaven; all generations shall praise thee with great joy. Cursed are all they which hate thee, and blessed shall all be which love thee for ever. Rejoice and be glad for the children of the just: for they shall be gathered together, and shall bless the Lord of the just. O blessed are they which love thee, for they shall rejoice in thy peace: blessed are they which have been sorrowful for all thy scourges; for they shall rejoice for thee, when they have seen all thy glory, and shall be glad for ever. Let my soul bless God the great King. For Jerusalem shall be built up with sapphires and emeralds, and precious stone: thy walls and towers and battlements with pure gold. And the streets of Jerusalem shall be paved with beryl and carbuncle and stones of Ophir. And all her streets shall say, Alleluia; and they shall praise him, saying, Blessed be God, which hath extolled it for ever.