A reunion of the huge Symon family is reluctantly attended by bankrupt businessman Raymond, his wife Esther and their surveyor son Daniel. Raymond has had no contact with the family for some time and his father was reg...展开arded as the 'black sheep'. Arriving at the hotel, Daniel meets his cousins Charles and Rebecca, and is fascinated by their sophisticated, cynical attitude, although he is immediately waylaid by Irving, a property speculator who wants to utilise his skills as a surveyor. Daniel and his family are invited to see Stephen, the family archivist, who has some photographs for them to look at. One is a picture of Daniel dressed as a prince while standing on a staircase. Another is a picture of Raymond as a boy laughing at his father performing some kind of dance. Little information is available about the photographs but Daniel is determined to find out more.
Daniel receives an invitation to escort Alice, Ernest's sister-in-law, to the reception, and the two find a rapport. Later, he is taken by Rebecca and Charles to see a family house in Grosvenor Place which he realises was the location for his 'prince' photograph. Meanwhile, Raymond meets Alice while searching for room service and he explains how he out of place he feels due to his financial problems.
The next day, Daniel meets Stephen who tells about his own heritage; Stephen's mother was a Jew who survived the war by posing as an Aryan and learning an invented family tree by heart. Daniel realises there are many family secrets. At the banquet, his fascination with the family is tempered by embarrassment when Raymond gets up and makes a drunken speech before collapsing with a stroke.
Raymond is taken to hospital and subsequently moved, much to his chagrin, into Ernest's London flat. Daniel and Esther stay on a little longer at the hotel, where they discover a story about two elderly female relatives who, during the war, walked from Wales to Birmingham and subsequently lived wild in the woods for nearly a year. This inspires Esther to begin researching her own family history with Stephen's assistance and the story of sibling love fascinates Daniel, an only child, and provokes him to find out more about Rebecca and Charles.
Rebecca arrives at the hotel and asks Daniel to act as a go-between. She is not speaking to Alice, and Daniel, perturbed, discovers that the problem is related to the third child, Richard, who died in a railway accident and who has been omitted from the family tree. Alice claims this was a clerical error but Rebecca believes it was malicious. Daniel is falling in love with Rebecca and they make love, although Rebecca is unsure that this is wise.
Returning to Alice to inform her that Rebecca hasn't forgiven her, Daniel insists on discovering the truth about the rift. He finds out that Alice, who was like a mother to Rebecca, Charles and Richard when they were young, feels partially responsible for Richard's death after he became mentally ill. Alice, along with the other two children, began to isolate Richard and avoid him because his illness was becoming an embarrassing nuisance. Richard died alone and confused at why the love of his family was abruptly withdrawn. Rebecca is consumed with guilt about his death and, unable to forgive herself, cannot forgive Alice either.
Daniel tries to engineer a reconciliation at a family party, but Rebecca refuses to compromise and walks away. He gives up but is diverted by Raymond's arrival with a solution to the mystery of the photographs. Raymond has discovered that in the photo of him as a boy, he was not looking at his father dancing but at his father's mistress - his sister-in-law - hiding in the trees. He shows Daniel a portrait of a little prince which belonged to his father's mistress and explains that Daniel was dressed like this as a parting love token from his grandfather to his long-time lover. Daniel realises that he has been a go-between right from when he was a child. The party begins with a speech from Alice in which she remembers Richard and reminds the guests of the importance of their memories.