Continue story, why? I would fix the open ending. Many of us at the book club found this a bit irritating. We understand the need for a series but the abrupt ending was not at all appealing.
5 major events in order? Sybil murdered. Cassie joined the secret society. Abraham sent Daniel and Leroy to find the missing artifact. Faye sent her crew to look for the artifact. Everyone came back without it.
Beginning of book? The beginning was Cassie dreaming about her sister being murdered which then sets the chain of events for the rest of the story.
Disclosure: I received a review copy of this book from the author.