Becky is the math whiz, but Sam is pretty sure he can count to four--or can he? Sam and Becky have visited a lot of lighthouses during their summer vacations (helping Mom and Dad write their book about lighthouses), so Sam knows how to count lighthouse flashes. Why is this one so different? For two whole weeks, Sam, Becky, Mom and Dad are staying on North Carolina's amazing Oak Island and sharing a house-- right on the beach--with Dad's best friend...