It is clear that Jo is once again very ill, and starving. He tells Woodcourt that he ran away from Esther, but he was "took away, by someone he dursn't name." He cannot keep straight the identities of Lady Dedlock, Hortense, and Esther Summerson.
At some point, we learn, Mr. Bucket put Jo in hospital, and when he was well he was discharged and told to "move on." Allan gives him wine and food, and takes him to Mr. George's shooting gallery. There he is received and aided, with the attendance of Dr. Woodcourt, but the child dies piteously, with the first prayer of his life, dictated by Dr. Woodcourt, on his lips.
Turning to Chapter 48, Lady Dedlock has resolved to remove Rosa from her employ, and place her with Mr. Rouncewell to be educated for his son, so as to save the girl from any taint when the scandal of their marriage comes out.
This development is a deal-breaker to Tulkinghorn, who sais that he will "undeceive" Sir Leicester in his own time. It will not be tonight, but it could be tomorrow, or soon thereafter, at a time of Tulkinghorn's own choosing. Mr. Rouncewell comes and collects Rosa, who does not want to leave, and the requisite political wrangling between Sir Leicester and he ensues.
Then the moment arrives: Tulkinghorn is found in his office, shot dead through the heart, just before ten o'clock.
In Chapter 49, we find the Bagnet household preparing for the birthday dinner of Mrs. Bagnet. George Rouncewell arrives for the happy occasion, but he is a little depressed by his debts and very saddened by the death, in his establishment, of little Jo. The Bagnets, especially Mrs. Bagnet, are sympathetic.
The slightly comedic and happy birthday dinner commences, and Bucket, claiming he saw Sgt George through the window, arrives unexpectedly. He spends a nice time with the family. After he leaves with George, he arrests him for Tulkinghorn's murder. He claims that Tulkinghorn had called him a murderous fellow, but Bucket is mistaken. When Tulkinghorn said that he was referring to the now-dead Gridley. Bucket receives the large reward given by Sir Leicester Dedlock.
The pathetic death of Jo is contrasted by the relief of the removal of the evil character of Tulkinghorn. There is no doubt that the world is a better place without him. However, no one believes that George killled Mr. Tulkinghorn, and the fact that the miscarriage of justice is carried out so quickly and incorrectlly by the likable Mr. Bucket makes the scene more dramatic.
Lady Dedlock's removal of the maid causing Tulkinghorn to break their agreement seems a bit arbitrary, but it is just like him to have such inscrutable standards. Lady Dedlock has shown herself to have an iron character, and she has become more admirable throughout the book. She is nicely contrasted with the lower class iron character of the ironmaster, Mr. Rouncewell.
The happy interlude at the Bagnets, again, is a kind of gentle relief to the difficult and heavy proceedings of the rest of the chapters. There is no doubt that they are a happy family, and it is a relief for George to have some respite with them, even if it's only short-lived.
The death of Tulkinghorn is beautifully described, the eerie and familiar stage of him alone, drinking his wine in his chambers: a perfect setting for a cold-blooded murder. He is seen to be eminently deserving of murder, and the readers are rewarded with his meaningful death after the meaningless death of Jo.