Aftershock.

Tangshan, 1976. Two seven-year-old twins are buried under the rubble of the deadliest earthquake of the 20th century. The rescue team explains to their mother that freeing either child will almost certainly result in the death of the other. Forced to make the most difficult decision of her life, she finally chooses to save her son. Though left behind as dead, the little girl miraculously survives, unbeknownst to her brother and mother.