Brother's text back to airline: F--- you

• Jack's elder sister is one of the passengers missing on Malaysia Airlines Flight 370


• He has taken leave of his job to join other MH370 relatives searching for answers in Beijing


• On Monday, Jack received a text announcing "none of those on board survived"


• He and other passengers have joined forces to push for more information and proof

Beijing, China (CNN) -- Jack's elder sister was returning from a holiday. Her connecting flight was through Kuala Lumpur on MH370. After news of the missing flight, Jack took leave from his job to come to Beijing in search of answers.

He shows me the text he received from Malaysia Airlines on his smartphone Monday night. This is the infamous text announcing that "none of those on board survived."

Jack scrolls down to the response he texted back in English, "F--- You", although he spelled out the word.

The fight is under way. Grief has turned to action.

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Inside a Beijing hotel room, Jack and eight other passengers' relatives crowd around three laptops on a coffee table.

They are discussing, downloading, organizing. What's the next move? There is purpose in the air.

They've already protested in front of the Malaysian embassy in China. Now they've decided to share with the media their smartphone video of meetings with Malaysian officials.

They have designated themselves the media committee.

Eighteen days ago, they were busy with jobs and family life. Today, these former strangers are now partners in a mission: to push for answers and find their loved ones.

They are not satisfied with the Malaysian government's explanation that satellite data indicates the plane most likely crashed in the southern part of the Indian Ocean.

The relatives want more information and tangible proof like debris.

"It's an irresponsible conclusion with no direct evidence," says Steve Wang, whose mother was on the flight. "If there is no evidence, we still have hope."

He's wearing a white t-shirt displaying blue Chinese characters that read: "Pray for the passengers of MH370. We wish you a safe return."

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