The House on the Gulf

The House on the Gulf is a thoroughly gripping mystery from beginning to end! I thought it was excellent and I couldn't put it down!
Britt Lassiter's family has never been well off. She's always lived with her single mother and older brother in ramshackle apartments, struggling to make ends meet. So of course it seems like a golden opportunity when Bran, her brother, gets offered a house-sitting job for the Marquises, an elderly couple in Florida. Everything is perfect- the Marquises allow Britt, Bran, and their mother to live in their house all summer while they vacation in New York. Britt's mother can finish enough college to qualify for a scholarship so she can fulfill her dreams of becoming a doctor. Yes, everything seems perfect- until Bran begins acting very strange and unsettled. Britt's investigating leads to one startling discovery after another; she finds that things are definitely not as they seem at the Marquises'!