How about Tigers in Red Weather by Liza Klaussmann? I really enjoyed it, and it's perfect for reading on the beach. Or This Is How It Ends by Kathleen MacMahon? Very good, but might be a bit too sad though.
Moon Island by Rosie Thomas is perfect for a beach holiday as it's set on a beach. It's just the right mix of intrigue with a spooky twist, great book. her other books are pretty good to.manything Phil Rickman writes is pretty unputdownable to.