Jehosheba was probably a young lady when her father became king, because her brother Ahaziah, was a teenager. When her father took the throne, he killed all of his brothers with the sword. Apparently he did not want his authority to be threatened. For Jehosheba, this meant that all of her paternal uncles were dead. Yet this was only the beginning of the madness...
Later, the prophet Elijah sent her father a letter. In the letter, he prophesied that misfortune would come upon him and his family because he had turned away from God and murdered his brothers. And misfortune came. First, raiders came and killed all of Jehosheba's brothers, except Ahaziah. Then, King Jehoram got a terrible intestinal disease. He died after two years of severe pain. In addition to uncles, Jehosheba had now lost her brothers and father.
Following all of this, Jehosheba's last brother Ahaziah was crowned king. One year into his rule, King Ahaziah's uncle, the King of the Northern Kingdom, was injured. King Ahaziah decided to go visit him. He took his dead brothers' children along with him. They served him on the journey. This trip, however, coincided with the judgment on the house of Ahab. And as Jehu killed those of Ahab's family, he saw the nephews of King Ahaziah there and killed them as well. Finally they tracked down King Ahaziah himself and killed him. Jehosheba had lost her last brother and many of her nephews.
After all of this, queen Athaliah, Jehosheba's mother, went wild. She set out to kill all the princes of Judah. Jehosheba was not about to let that happen. She somehow managed to rescue her infant nephew Joash before her mother could kill him. Jehosheba took him to the temple to hide him. Her husband was a priest in the temple and his name was Jehoiada. Jehoiada was between 90-120 years old at the time, but he still commanded respect. After waiting six years, he organized for Joash to be anointed as king and given the throne. At that time, queen Athaliah was finally removed from rule and executed. King Joash was only 7 years old. Jehoiada continued to guide and support the young king until his death at the age of 130. King Joash ended up ruling for a total of 40 years. There is no mention of Jehosheba.
Now, I am pretty sure I got that right. The original is in II Kings 8, 11-12 and II Chronicles 21-23. I must say, history is more intriguing than anything I could think up!