In December of 2004, a family of five decided to travel to Thailand for Christmas. As the were relaxing by the pool they were unexpectedly struck by a deadly tsunami. The eldest son Lucas had separated from the rest of the family, but would later reunite with his mother Maria. Even though Lucas had already faced so much, he had to show resiliency in order to take care of his wounded mother and a child they had rescued until help would come.
In this scene, Maria and Lucas had been rescued by the locals and sent to the hospital for their injuries. Lucas concerns for his mother begin to worsen, as her injuries have yet to improve. Not to aid in the matter, but his mother believes if she should succumb to her injuries Lucas would be alone in the world. Lucas had to remain calm and strong for his mother, and most likely had to act more mature than he's ever had to.
In this part of the film, Maria tells Lucas to see if there is anyone he can help so that he can clear his mind, as there is nothing he can do to help her. Lucas decides to help those who are looking for their loved ones that may be in the hospital. After a long while, he finally finds someone, the son of a man he offered to help and they were all extremely overjoyed.
As learned from the previous scene Lucas helped others find their loved ones and couldn't wait to tell his mother, but when he returned to his mom's room she was gone. The nurses were unsure of where Maria was, so a woman who I believe to be a social worker, toke Lucas to the area for unclaimed or orphaned children. This is where Lucas broke down and was really at the point where he felt completely alone.
Fortunately, Lucas found Maria but her condition had only worsened and the doctors believed she was going to need multiple surgeries. As Lucas was going to get some water he thought that he saw his father, but when he went searching for him he couldn't find him in the crowd of people. Right when he was about to give up, he heard his younger brothers Thomas and Simon screaming for him. Well their father heard them and they were all reunited.
By the end of the movie, Maria was well enough to travel and the family was together again heading home. Even though Lucas had gone through so much in the past few days, from surviving a tsunami to thinking his whole family was gone, his resilience is what helped him to continue.