A young man discovers a well-kept secret in his family's past in this coming-of-age drama from Singapore. Eighteen-year-old En (Joshua Tan) is not enthusiastic when his mother (Elena Chia) announces she's going on vacation with her boyfriend (Samuel Chong) and that he'll have to stay with his grandparents while she's gone. En doesn't have much in common with his grandfather, and his grandmother is struggling with Alzheimer's Disease and communicating with her is difficult. While grandmother occasionally refers to her husband's subversive past, En discovers a box of photos that suggest he was a student activist who took part in anti-government protests in the 1950s. En is fascinated by this revelation, but grandfather dies suddenly before he can ask him about it, and the rest of his family is hesitant to discuss the past. Meanwhile, as grandmother moves in with En and his mom, the teenager ends up sharing a room with the elderly woman, which becomes even more of a problem when En begins dating a pretty girl from the neighborhood (Bobbi Chen), though his new girl may hold a key in unraveling the truth about grandfather's past. Sandcastle was the first feature film from director and screenwriter Boo Junfeng.