What would Matt have to do now that Ben had taken the rifle with him?

The Sign of the Beaver by Elizabeth Speare opens with the main character, Matt, guarding the cabin he built with his father. Matt's dad was leaving to go back to Massachusetts to bring his wife, daughter, and new baby to the newly built cabin in Maine to live. Matt was going to be on his own for six to seven weeks. Matt's dad left him his rifle so Matt could hunt for food as well as protect himself.
One day while Matt is cooking his supper, a stranger comes out of the trees and says hello to Matt. This stranger is named Ben, and he asks Matt questions about his family. Ben invites himself to supper, and Matt learns that Ben plans to live with the Indians. While in the cabin, Ben admires the rifle and asks questions about Matt's family. After supper, Ben falls asleep and Matt cleans up. Matt begins to become uneasy about Ben and starts worrying about how long Ben plans to stay. Matt wonders if he should trust Ben. Matt decides to be sensible and stay awake to guard the cabin. Unfortunately, when Matt wakes up after falling asleep, both Ben and the rifle are gone.
With no rifle, Matt cannot protect himself or hunt for food. Matt needs to learn how to protect himself another way, such as with a bow and arrows. He also needs to learn to catch fish and what is safe to eat in the woods and what is not. Maybe a member of one of the local Indian tribes can teach Matt how to grow crops and what to eat in the forest. Matt needs to live on his own without his father's rifle for many more weeks. Maybe the Indians can teach Matt how to use other ways to hunt for food without a gun. Matt is also going to have to figure out what to say to his dad about losing the rifle. Ben taking the rifle creates all these problems for Matt to solve.