This family was built on betrayal. The four branches of the family have been at it since the very beginning, when four petty siblings got into a fight that they just couldn't resolve. The fight has lasted for generations and we see no signs of it coming to a close any time soon. Until then, there are going to be a lot of knives in a lot of backs, which makes airline travel really difficult.
Questions About Betrayal
Did Grace betray Amy and Dan by not telling them about the contest ahead of time?
Over the course of the novel, which Cahills betray others and why?
Is William McIntyre betraying Amy and Dan's trust by not revealing his association with the mysterious man in black?
Chew on This
Fool us once, shame on you. Fool us twice, shame on us. Amy and Dan come from a family of betrayal. They should have been expecting it the second time Uncle Alistair betrayed their trust.
About the only person in this book who deserves absolute loyalty isn't even a person; it's Saladin the cat. And even he gets betrayed by being passed off to a non-animal person: William McIntyre.