The Secret Detectives

On board the S.S. Mariana, Isobel Petty witnesses a shocking act - somebody being thrown overboard in the middle of the night. But, when the ship's captain insists that nobody is missing, Isobel and her friends must solve two mysteries - the identities of both the murderer and the victim.

Can they do it before the ship reaches England the the culprit has a chance to escape?