Complex sentence: Laura is saddened by the loss of a potential friend, and longs for a companion until a carriage accident outside Laura's home unexpectedly brings Carmilla, a girl of Laura's age, into the family's care.
Split into simpler sentences: Laura is saddened by the loss of a potential friend, and longs for a companion. A carriage accident outside Laura's home unexpectedly brings a girl of Laura's age into the family's care.