diff --git a/lib/telebugs.rb b/lib/telebugs.rb
index 0bfdb91..2b99af2 100644
--- a/lib/telebugs.rb
+++ b/lib/telebugs.rb
@@ -13,6 +13,8 @@
 require_relative "telebugs/notice"
 require_relative "telebugs/error_message"
 require_relative "telebugs/backtrace"
+require_relative "telebugs/file_cache"
+require_relative "telebugs/code_hunk"
 
 module Telebugs
   # The general error that this library uses when it wants to raise.
diff --git a/lib/telebugs/code_hunk.rb b/lib/telebugs/code_hunk.rb
new file mode 100644
index 0000000..3f386e8
--- /dev/null
+++ b/lib/telebugs/code_hunk.rb
@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+module Telebugs
+  # Represents a small hunk of code consisting of a base line and a couple lines
+  # around it
+  class CodeHunk
+    MAX_LINE_LEN = 200
+
+    # How many lines should be read around the base line.
+    AROUND_LINES = 2
+
+    def self.get(file, line)
+      start_line = [line - AROUND_LINES, 1].max
+
+      lines = get_lines(file, start_line, line + AROUND_LINES)
+      return {start_line: 0, lines: []} if lines.empty?
+
+      {
+        start_line: start_line,
+        lines: lines
+      }
+    end
+
+    private_class_method def self.get_lines(file, start_line, end_line)
+      lines = []
+      return lines unless (cached_file = get_from_cache(file))
+
+      cached_file.with_index(1) do |l, i|
+        next if i < start_line
+        break if i > end_line
+
+        lines << l[0...MAX_LINE_LEN].rstrip
+      end
+
+      lines
+    end
+
+    private_class_method def self.get_from_cache(file)
+      Telebugs::FileCache[file] ||= File.foreach(file)
+    rescue
+      nil
+    end
+  end
+end
diff --git a/lib/telebugs/config.rb b/lib/telebugs/config.rb
index 7bf0e08..a0c6274 100644
--- a/lib/telebugs/config.rb
+++ b/lib/telebugs/config.rb
@@ -6,7 +6,9 @@ module Telebugs
   class Config
     ERROR_API_URL = "https://api.telebugs.com/2024-03-28/errors"
 
-    attr_accessor :api_key
+    attr_accessor :api_key,
+      :root_directory
+
     attr_reader :api_url
 
     class << self
@@ -28,6 +30,10 @@ def api_url=(url)
     def reset
       self.api_key = nil
       self.api_url = ERROR_API_URL
+      self.root_directory = File.realpath(
+        (defined?(Bundler) && Bundler.root) ||
+        Dir.pwd
+      )
     end
   end
 end
diff --git a/lib/telebugs/file_cache.rb b/lib/telebugs/file_cache.rb
new file mode 100644
index 0000000..d88ae13
--- /dev/null
+++ b/lib/telebugs/file_cache.rb
@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+module Telebugs
+  module FileCache
+    MAX_SIZE = 50
+    MUTEX = Mutex.new
+
+    # Associates the value given by +value+ with the key given by +key+. Deletes
+    # entries that exceed +MAX_SIZE+.
+    def self.[]=(key, value)
+      MUTEX.synchronize do
+        data[key] = value
+        data.delete(data.keys.first) if data.size > MAX_SIZE
+      end
+    end
+
+    # Retrieve an object from the cache.
+    def self.[](key)
+      MUTEX.synchronize do
+        data[key]
+      end
+    end
+
+    # Checks whether the cache is empty. Needed only for the test suite.
+    def self.empty?
+      MUTEX.synchronize do
+        data.empty?
+      end
+    end
+
+    def self.reset
+      MUTEX.synchronize do
+        @data = {}
+      end
+    end
+
+    private_class_method def self.data
+      @data ||= {}
+    end
+  end
+end
diff --git a/lib/telebugs/notice.rb b/lib/telebugs/notice.rb
index e29eacd..4d62f03 100644
--- a/lib/telebugs/notice.rb
+++ b/lib/telebugs/notice.rb
@@ -46,11 +46,27 @@ def errors_as_json(error)
         {
           type: e.class.name,
           message: ErrorMessage.parse(e),
-          backtrace: Backtrace.parse(e)
+          backtrace: attach_code(Backtrace.parse(e))
         }
       end
     end
 
+    def attach_code(b)
+      b.each do |frame|
+        next unless frame[:file]
+        next unless File.exist?(frame[:file])
+        next unless frame[:line]
+        next unless frame_belogns_to_root_directory?(frame)
+        next if %r{vendor/bundle}.match?(frame[:file])
+
+        frame[:code] = CodeHunk.get(frame[:file], frame[:line])
+      end
+    end
+
+    def frame_belogns_to_root_directory?(frame)
+      frame[:file].start_with?(Telebugs::Config.instance.root_directory)
+    end
+
     def truncate
       0
     end
diff --git a/test/fixtures/project_root/code.rb b/test/fixtures/project_root/code.rb
new file mode 100644
index 0000000..8d7e2d0
--- /dev/null
+++ b/test/fixtures/project_root/code.rb
@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+class Botley
+  RESPONSES = {
+    /hello/i => "Oh, hello there! Are you ready to have some fun?",
+    /how are you/i => "I'm just a bunch of code, but thanks for asking! How about you?",
+    /what is your name/i => "I'm Botley, your friendly (and sometimes cheeky) virtual assistant!",
+    /joke/i => "Why don't scientists trust atoms? Because they make up everything!",
+    /bye|goodbye|exit/i => "Goodbye! Don't miss me too much!",
+    /thank you|thanks/i => "You're welcome! I'm here all week.",
+    /default/ => "I'm not sure what you mean, but it sounds intriguing!"
+  }
+
+  def initialize
+    puts "Botley: Hello! I'm Botley, your virtual assistant. Type 'goodbye' to exit."
+  end
+
+  def start
+    loop do
+      print "You: "
+      user_input = gets.chomp
+      response = respond_to(user_input)
+      puts "Botley: #{response}"
+      break if user_input.match?(/bye|goodbye|exit/i)
+    end
+  end
+
+  private
+
+  def respond_to(input)
+    RESPONSES.each do |pattern, response|
+      return response if input.match?(pattern)
+    end
+    RESPONSES[:default]
+  end
+end
+
+# Start the conversation with Botley
+Botley.new.start
diff --git a/test/fixtures/project_root/empty_file.rb b/test/fixtures/project_root/empty_file.rb
new file mode 100644
index 0000000..e69de29
diff --git a/test/fixtures/project_root/long_line.rb b/test/fixtures/project_root/long_line.rb
new file mode 100644
index 0000000..1973950
--- /dev/null
+++ b/test/fixtures/project_root/long_line.rb
@@ -0,0 +1 @@
+loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong line
diff --git a/test/fixtures/project_root/one_line.rb b/test/fixtures/project_root/one_line.rb
new file mode 100644
index 0000000..e421822
--- /dev/null
+++ b/test/fixtures/project_root/one_line.rb
@@ -0,0 +1 @@
+Boom.new.call
diff --git a/test/test_code_hunk.rb b/test/test_code_hunk.rb
new file mode 100644
index 0000000..4a74642
--- /dev/null
+++ b/test/test_code_hunk.rb
@@ -0,0 +1,87 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class TestCodeHunk < Minitest::Test
+  def test_get_when_file_is_empty
+    hunk = Telebugs::CodeHunk.get("test/fixtures/project_root/empty_file.rb", 1)
+
+    assert_equal({start_line: 0, lines: []}, hunk)
+  end
+
+  def test_get_when_file_has_one_line
+    hunk = Telebugs::CodeHunk.get("test/fixtures/project_root/one_line.rb", 1)
+
+    assert_equal(
+      {
+        start_line: 1,
+        lines: ["Boom.new.call"]
+      },
+      hunk
+    )
+  end
+
+  def test_get
+    hunk = Telebugs::CodeHunk.get("test/fixtures/project_root/code.rb", 18)
+
+    assert_equal(
+      {
+        start_line: 16,
+        lines: [
+          "  end",
+          "",
+          "  def start",
+          "    loop do",
+          "      print \"You: \""
+        ]
+      },
+      hunk
+    )
+  end
+
+  def test_get_with_edge_case_first_line
+    hunk = Telebugs::CodeHunk.get("test/fixtures/project_root/code.rb", 1)
+
+    assert_equal(
+      {
+        start_line: 1,
+        lines: [
+          "# frozen_string_literal: true",
+          "",
+          "class Botley"
+        ]
+      },
+      hunk
+    )
+  end
+
+  def test_get_with_edge_case_last_line
+    hunk = Telebugs::CodeHunk.get("test/fixtures/project_root/code.rb", 39)
+
+    assert_equal(
+      {
+        start_line: 37,
+        lines: [
+          "",
+          "# Start the conversation with Botley",
+          "Botley.new.start"
+        ]
+      },
+      hunk
+    )
+  end
+
+  def test_get_when_code_line_is_too_long
+    hunk = Telebugs::CodeHunk.get("test/fixtures/project_root/long_line.rb", 1)
+
+    assert_equal(
+      {
+        start_line: 1,
+        lines: [
+          "loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong"
+        ]
+      },
+      hunk
+    )
+  end
+end
diff --git a/test/test_config.rb b/test/test_config.rb
index 3a79076..4d4e7e4 100644
--- a/test/test_config.rb
+++ b/test/test_config.rb
@@ -18,4 +18,10 @@ def test_error_api_url
 
     assert_equal URI("example.com"), Telebugs::Config.instance.api_url
   end
+
+  def test_root_directory
+    Telebugs.configure { |c| c.root_directory = "/tmp" }
+
+    assert_equal "/tmp", Telebugs::Config.instance.root_directory
+  end
 end
diff --git a/test/test_file_cache.rb b/test/test_file_cache.rb
new file mode 100644
index 0000000..b8ae010
--- /dev/null
+++ b/test/test_file_cache.rb
@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class TestFileCache < Minitest::Test
+  def teardown
+    Telebugs::FileCache.reset
+  end
+
+  def test_set_when_cache_limit_is_not_reached
+    max_size = Telebugs::FileCache::MAX_SIZE
+    max_size.times do |i|
+      Telebugs::FileCache["key#{i}"] = "value#{i}"
+    end
+
+    assert_equal "value0", Telebugs::FileCache["key0"]
+    assert_equal "value#{max_size - 1}", Telebugs::FileCache["key#{max_size - 1}"]
+  end
+
+  def test_set_when_cache_over_limit
+    max_size = 2 * Telebugs::FileCache::MAX_SIZE
+    max_size.times do |i|
+      Telebugs::FileCache["key#{i}"] = "value#{i}"
+    end
+
+    assert_nil Telebugs::FileCache["key49"]
+    assert_equal "value50", Telebugs::FileCache["key50"]
+    assert_equal "value#{max_size - 1}", Telebugs::FileCache["key#{max_size - 1}"]
+  end
+end
diff --git a/test/test_notice.rb b/test/test_notice.rb
index 4b6f091..3aabe78 100644
--- a/test/test_notice.rb
+++ b/test/test_notice.rb
@@ -3,6 +3,24 @@
 require "test_helper"
 
 class TestNotice < Minitest::Test
+  def fixture_path(filename)
+    File.expand_path(File.join("test", "fixtures", filename))
+  end
+
+  def project_root_path(filename)
+    fixture_path(File.join("project_root", filename))
+  end
+
+  def setup
+    Telebugs.configure do |c|
+      c.root_directory = project_root_path("")
+    end
+  end
+
+  def teardown
+    Telebugs::Config.instance.reset
+  end
+
   def test_to_json_with_nested_errors
     begin
       raise StandardError.new("error 1")
@@ -22,10 +40,44 @@ def test_to_json_with_nested_errors
     assert_equal "error 2", error1["message"]
     assert error1.key?("backtrace")
     assert error1["backtrace"].size > 0
+    assert_nil error1["backtrace"][0]["code"]
 
     assert_equal "StandardError", error2["type"]
     assert_equal "error 1", error2["message"]
     assert error2.key?("backtrace")
     assert error2["backtrace"].size > 0
+    assert_nil error2["backtrace"][0]["code"]
+  end
+
+  def test_to_json_code
+    error = RuntimeError.new
+    error.set_backtrace([
+      "#{project_root_path("code.rb")}:18:in `start'",
+      fixture_path("notroot.txt:3:in `pineapple'"),
+      "#{project_root_path("vendor/bundle/ignored_file.rb")}:2:in `ignore_me'"
+    ])
+
+    n = Telebugs::Notice.new(error)
+    json = JSON.parse(n.to_json)
+    backtrace = json["errors"][0]["backtrace"]
+
+    assert_equal 3, backtrace.size
+
+    assert_equal(
+      {
+        "start_line" => 16,
+        "lines" => [
+          "  end",
+          "",
+          "  def start",
+          "    loop do",
+          "      print \"You: \""
+        ]
+      },
+      backtrace[0]["code"]
+    )
+
+    assert_nil backtrace[1]["code"]
+    assert_nil backtrace[2]["code"]
   end
 end