Simplify the following text for a Grade 4 native English-speaking person.
Original: After arriving by train and eluding Combine forces , Gordon joins an underground resistance organized by fellow friends and scientists from Black Mesa , including Barney Calhoun and Alyx , the daughter of his former colleague , Dr. Eli Vance .
Simplified: He is part of the resistance . Alyx Vance is Eli 's daughter .