Resident Evil 0:
Wesker send the Bravo Team to investigate. Theirs helicopter crashes and they split, one team to the mansion and second to the stopped train. Rebecca is in the second team. She mets Billy Cohen a convict and they tries to escape from the horror.

Resident Evil:
Alpha Team goes after Bravo Team and they end up in the mansion after Brad have left them. And Chris,Jill and Barry fight zombies and monster AND Wesker. In the end Barry knocked down Wesker and they escaped when Brad came back

Resident Evil 2:
Claire Redfield comes to Raccon City to find her brother
and Leon S Kennedy came to the city on his first day on the job has a RPD. They are trying escape. Claire mets little girl named sherry Birkin and they escape with Leon who has met Ada wong but she died. They escape with a train.

Resident Evil 3:
Jill is left in the city and trying to help all humans and in the same time to escape. She mets Carlos who is a Umbrella soldier. And a Monster is after STARS so she has a big problem. She escape with Carlos thanks to Barry Burton who came looking for her.

Resident Evil Code:Veronica
Claire is still looking after Chris. She is in Paris but Umbrella capture her. She cames to Ashford island.
and the island is infected with zombies. She meets a boy named Steve Burnside(Many says he looks like Leon DiCaprio)
they escape from the island but they landed in Antartic and there where to infected. Chris came after Claire when he heard that she was captured. And he meets Albert Wesker.
He find his sister and escapes with her and steve died of T-Veronica so Albert Wesker took his body with him because Steve was infected with T-Veronica and Weskers mission was to collect T-Veronica

Resident Evil 4:
I dont know anything 100% about this game

Resident Evil Gaiden:
Only that i know is that it is on a cruiser ship and Leon Scott Kennedy and Barry Burton is in the game and one girl named Lucia.

I have write a little if you want to know more play the game