In a previous novel A Surprising Legacy Amos Carlisle becomes a victim of a land grab by the aristocracy at the time of the Enclosures Act. Taking to the road in a horse drawn caravan, he befriends a small child, Ruth, whose mother has been jailed for vagrancy. When her mother, Sarah, is eventually released from prison he offers them a home.Fortune befalls them when Ruth and Sarah inherit a legacy from Sarah's former lover and Ruth's father, Joseph Craven, who dies as a soldier in the New World.In The Lightning Tree, set in the late 1700s, Sarah and Amos marry and settle in a country cottage but are soon faced with a challenge that could divest them of the legacy and threaten their marriage.A man who purports to be Sir Duncan Carew MP., and his son Matthew, arrive at their door with news that Sarah's former lover and benefactor, Joseph Craven, did not die but actually deserted from his post in the army. At this stage a character is introduced into the story who purports to be Joseph Craven but he has such severe facial disfigurement that even Sarah cannot be sure whether or not this is her former lover. This person is very ill with tuberculosis but Amos installs him in the caravan in the garden of his home and he is nursed back to a healthier state. Apparently he faces the gallows - presumably for desertion and perhaps murder. Together the family face the dilemma of whether or not to return at least some of the legacy to him. The matter is both a question of legality and of Christian morality. They are implored by the Carews to keep his presence a secret because of the threat of capital punishment hanging over him. Sarah becomes inclined to be benevolent towards him - half convinced of his story- whilst Amos, more down to earth, increasingly believes him and the Carews to be imposters out to swindle. Ruth, who was still a baby when her father left for the New World, desperately wants the man to be her real father. In this dilemma the family risk being torn apart.A spate of house burglaries and the death of a promiscuous young girl bring Inspector Wilkins into the story. Amos follows the supposed Joseph Craven during his nocturnal nefarious activities and sees him secrete his ill gotten gains in the hollow of the lightning tree. Amos returns to the tree during daylight hours to check what has been secreted and he is discovered by Inspector Wilkins and forced to reveal all about the 'Joseph Craven' living in the caravan. Because of his disclosure both Sarah and Ruth become at odds with Amos, fearing he has condemned Ruth's father to the gallows.When the police become interested in 'Joseph' he disappears but re-appears to Ruth asking her to pressure Amos for money. When Amos refuses, 'Joseph' holds Ruth hostage trying to force his hand. She escapes and now everyone is aware that this was a huge conspiracy from the outset. There is a hue and cry to find 'Joseph' but he is eventually detained having broken into Sarah's home during the night whilst Amos was elsewhere.There are other side issues throughout the story which mention historical world events that are as accurate as possible.The story ends with the imposter 'Joseph' in jail contemplating suicide rather than face the prospect of a second transportation to Van Daemon's Land, and the two imposter Carews on the run. The real Sir Duncan Carew MP visits the family, concerned that his name has been used to perpetrate this crime.