The Agathas by Kathleen Glasgow and Liz Lawson

The most popular girl in school is dead. And everyone’s blaming the wrong guy. After falling from grace last summer, Agatha Christie-obsessed Alice Ogilvie needs to stay out of trouble. While smart and reclusive Iris Adams just wants to get the hell out of Castle Cove. But now they have a murder to solve. There are clues the police are ignoring, a list of suspects a mile long and some very dangerous cliffs. Amateur detectives Alice and Iris are about to uncover just how many secrets their sleepy seaside town is hiding. This book is available in paperback.