"If you defeat multiple enemies in a row, you'll get yourself a nice bonus!"
— Josh to the player via radio in The Mercenaries mode
Josh Stone is a member of the Bioterrorism Security Assessment Alliance's (BSAA) West Africa division, although upon further inspection. Josh was the Captain of the first team Sheva Alomar joined with the BSAA and trained Sheva for eight months. After the training was complete, Sheva and Stone developed an extremely close relationship in which he refers to Sheva as "the little sister of the team".
Josh first appears at the crash site of the downed helicopter flown by Kirk Mathison. Josh and his team help Chris Redfield and Sheva as the two are being overrun by Majini. Chris, Sheva, and Josh reunite at the train yard. Josh and Chris introduce themselves and Chris is surprised to see that Josh and Sheva already know each other. Sheva tells Chris that she trained under Josh, and that Josh thinks of Sheva as a little sister. Josh then hands Chris a PDA that has information on it. Some containing a picture of Chris' former partner Jill Valentine. Josh then exits the room, and later on is attacked by a B.O.W. that was released by Excella Gionne. Josh runs into Chris and Sheva at the Oil Refinery alone after his team was wiped out. Josh and Sheva have a brief moment, and Josh then asks the two why they didn't retreat. Chris states that he is here more on personal terms rather than the mission, and Sheva explains the situation about Jill. The trio are then attacked by Majini, fighting off relentless waves of them. Josh unlocks the elevator and they make it up to a higher level. Josh then unlocks another door, which leads to their safety. At this point, Josh leaves Chris and Sheva behind. As the oil refinery is about to explode due to Ricardo Irving. Josh rescues Chris and Sheva in a speedboat moments before the oil refinery finally explodes. The team make it just out of reach from the explosion, and they decide that it's time to stop Irving once and for all. Josh, Chris, and Sheva are floating in the boat until Majini in speed boats come and attack them. The team are shot at and Chris and Sheva take them out as Josh drives them out of danger. Through the mist, Irving's boat comes out of nowhere and Josh slams into the side of his boat by mistake. Chris and Sheva take out the Majini shooting at them from the boat and then they get on board. Irving mutates, thanks to a sample Jill gave to him. Josh then leaves the area under Chris' orders. After Irving is defeated, he reveals to Chris that all of the answers he wants awaits him in the caves. Josh takes Chris and Sheva to the caves and then retreats to headquarters. He then went back and followed Chris and Sheva, although they didn't realize that.
Josh enters the Monarch Room just missing Chris and Sheva, the two he came back for. As he heads up the stairs he notices a woman passed out. As he wakes the woman, he realizes that she is the one and only Jill Valentine. He helps her up and he reveals to her that he is looking for Chris and Sheva. Jill tells him that they just went after Albert Wesker, and that he is aboard a tanker. Josh tells Jill that he has a helicopter waiting and he is going after Sheva. He agrees to take Jill along, after flirting a little with her, and the two leave the room. Jill tells Josh that she had to go to the communication facility in order to tell Chris how to defeat Wesker. Throughout their journey, the two are attacked by waves and waves of Majini. Josh and Jill use the Majinis' weapons to their advantage, seeing as if it is the only way to escape. Once they reach the facility, Jill contacts Chris, with Josh's help, and she tells him that an overdose should do the trick. The radio is cut and Josh and Jill exit to the rooftop. Doug, the BSAA agent who has the helicopter, has not reached the rooftop yet. Josh and Jill are forced to fight off Majini until Doug finally arrives. Once there, Jill is blown back by a blast from a rocket launcher. Josh helps Jill to the helicopter and notices Doug is not aboard yet. Doug is then killed by the same man who tried to kill Jill. Jill holds off other Majini along with Killing the Majini with the RPG. Josh flies the two out of the area, and they both agree to help Chris and Sheva with their fight against Wesker.