Alton Hollett is the twin brother of Frank Hollett, the owner of Hollett Construction. He came to Guernsey when searching for Frank 25 years ago, but went missing from his guesthouse. A police search ensued but his body was never recovered.
He is first mentioned in book 1, Dead in the Water, when the case of his disappearance is being investigated. Book 2, Blowfish, picks up the story from the point where he originally arrived in the garden.
Although Frank and Alton haven’t seen each other for many years when they are first reunited upon Alton’s arrival on the island, the similarities between the two remain obvious.