Sister traveling across the country to pick up someone’s “daughter”

My sister has been talking to a dude online for about 6 months now. He’s an offshore oil & gas worker and is currently offshore while his daughter is homed with a family friend who is increasingly getting upset about taking in this child. Apparently, his contract was supposed to end this month but was extended due to some equipment malfunction or something of the sorts. And so now, this babysitter is mistreating his daughter and needs to be rescued. Apparently, there are no other family members or friends that can help. My sister has taken it upon herself to drive across the country to pick up said daughter and drive back.

I’m genuinely concerned this is child trafficking or the very least, a scam of some sort. What do you think? Has anyone ever heard of something similar before?

Update:

She’s said she’s given no money and he hasn’t asked. They do phone calls and he’s open to video chatting but she hasn’t accepted.

I’m now doing a full on investigation into this company he supposedly works for to get legitimate proof it’s a scam. I’m honestly going to be emailing them and hope they reply with confirmation. I need evidence to get through her head.

Final Update:

She's not going. Thank GOD. He told her he wasn't comfortable having her travel alone. He also refused to let her purchase an airplane ticket because it's too expensive. So, if this dude isn't a scam, he's a real shitty father.

The letter she shared with me has a Gmail address for the supposed Vice President for a major oil & gas company. Yea...no. I also called the number listed and went to voicemail with no message set. Now they're texting me and asking who I am.

This whole situation is whack. I told her this whole idea of picking up a minor and traveling across state lines is not only dangerous, but illegal. Also told her she needs to get her own shit straight emotionally and financially before she tries to be someone else's hero. She still believes he’s legit. She’s well into her 40s….I can’t force her to stop talking to him. I’m just glad she’s not going.