What is the main conflict in The Shell Seekers by Rosamunde Pilcher?

Penelope has just suffered a slight heart attack at the beginning of the novel and she is happy to return home (after voluntarily checking herself out of the hospital.) She then decides that it is time for her to return to Porthkerris, where she lived throughout World War II and met the love of her life, Richard. She asks each of her three children to come with her to make the trip, but all three decline.