Definitely Grace.

"Is there a problem?" Melanie asked when she noticed the way both Grace and Tae-Joon were staring at her with their mouth agape while Tae-Joon still held the phone to his ear. 

"No. Not at all," Grace said with a forced laughter even though her heart was thumping wildly. Melanie was their mother? How on earth? What was going on with everybody?

"I will see you soon. We are on our way there," Brad said, bringing Tae-Joon back to the present. 

"We? Who are you bringing with you?" Tae-Joon asked the question on Grace's mind too.

"Just some friends. You will meet them when we get there," Brad said before hanging up. 

"This is crazy!" Tae-Joon murmured to himself and closed his eyes to calm himself. His heart was beating erratically, and he felt like he couldn't breathe. This was his mother? Was that why he had felt a kind of connection to her? Did she know who he was? Was that why she had been looking at him since they met?