diff --git a/test/api/v3/integration/quests/POST-groups_groupId_quests_force-start.test.js b/test/api/v3/integration/quests/POST-groups_groupId_quests_force-start.test.js
index e569b14c33..bf295ee892 100644
--- a/test/api/v3/integration/quests/POST-groups_groupId_quests_force-start.test.js
+++ b/test/api/v3/integration/quests/POST-groups_groupId_quests_force-start.test.js
@@ -149,5 +149,87 @@ describe('POST /groups/:groupId/quests/force-start', () => {
       expect(partyMemberThatIgnores.party.quest.key).to.not.exist;
       expect(partyMemberThatIgnores.party.quest.completed).to.not.exist;
     });
+
+    it('removes users who have not accepted the quest from quest.members', async () => {
+      let partyMemberThatRejects = partyMembers[1];
+      let partyMemberThatIgnores = partyMembers[2];
+      let partyMemberThatAccepts = partyMembers[0];
+
+      await leader.post(`/groups/${questingGroup._id}/quests/invite/${PET_QUEST}`);
+      await partyMemberThatAccepts.post(`/groups/${questingGroup._id}/quests/accept`);
+      await partyMemberThatRejects.post(`/groups/${questingGroup._id}/quests/reject`);
+
+      await leader.post(`/groups/${questingGroup._id}/quests/force-start`);
+
+      await Bluebird.delay(500);
+
+      await questingGroup.sync();
+
+      expect(questingGroup.quest.members[partyMemberThatRejects._id]).to.not.exist;
+      expect(questingGroup.quest.members[partyMemberThatIgnores._id]).to.not.exist;
+      expect(questingGroup.quest.members[partyMemberThatAccepts._id]).to.exist;
+      expect(questingGroup.quest.members[leader._id]).to.exist;
+    });
+
+    it('removes users who are not in the party from quest.members', async () => {
+      await leader.post(`/groups/${questingGroup._id}/quests/invite/${PET_QUEST}`);
+      let notInPartyUser = await generateUser();
+
+      await questingGroup.update({
+        [`quest.members.${notInPartyUser._id}`]: true,
+      });
+      await questingGroup.sync();
+
+      expect(questingGroup.quest.members[notInPartyUser._id]).to.eql(true);
+
+      await leader.post(`/groups/${questingGroup._id}/quests/force-start`);
+
+      await Bluebird.delay(500);
+
+      await questingGroup.sync();
+
+      expect(questingGroup.quest.members[notInPartyUser._id]).to.not.exist;
+    });
+
+    it('removes users who have been deleted from quest.members', async () => {
+      await leader.post(`/groups/${questingGroup._id}/quests/invite/${PET_QUEST}`);
+      await partyMembers[0].post(`/groups/${questingGroup._id}/quests/accept`);
+
+      await partyMembers[0].del('/user', {
+        password: 'password',
+      });
+
+      await leader.post(`/groups/${questingGroup._id}/quests/force-start`);
+
+      await Bluebird.delay(500);
+
+      await questingGroup.sync();
+
+      expect(questingGroup.quest.members[partyMembers[0]._id]).to.not.exist;
+    });
+
+    it('removes users who don\'t have true value in quest.members from quest.members', async () => {
+      let partyMemberThatRejects = partyMembers[1];
+      let partyMemberThatIgnores = partyMembers[2];
+
+      await leader.post(`/groups/${questingGroup._id}/quests/invite/${PET_QUEST}`);
+      await partyMembers[0].post(`/groups/${questingGroup._id}/quests/accept`);
+
+      await questingGroup.update({
+        [`quest.members.${partyMemberThatRejects._id}`]: false,
+        [`quest.members.${partyMemberThatIgnores._id}`]: null,
+      });
+
+      await leader.post(`/groups/${questingGroup._id}/quests/force-start`);
+
+      await Bluebird.delay(500);
+
+      await questingGroup.sync();
+
+      expect(questingGroup.quest.members[partyMemberThatRejects._id]).to.not.exist;
+      expect(questingGroup.quest.members[partyMemberThatIgnores._id]).to.not.exist;
+      expect(questingGroup.quest.members[partyMembers[0]._id]).to.exist;
+      expect(questingGroup.quest.members[leader._id]).to.exist;
+    });
   });
 });
diff --git a/website/server/models/group.js b/website/server/models/group.js
index 5eee28f5e9..d5aa3d4536 100644
--- a/website/server/models/group.js
+++ b/website/server/models/group.js
@@ -393,6 +393,17 @@ schema.methods.startQuest = async function startQuest (user) {
   let nonUserQuestMembers = _.keys(this.quest.members);
   removeFromArray(nonUserQuestMembers, user._id);
 
+  // remove any users from quest.members who aren't in the party
+  let partyId = this._id;
+  let questMembers = this.quest.members;
+  await Bluebird.map(Object.keys(this.quest.members), async (memberId) => {
+    let member = await User.findOne({_id: memberId, 'party._id': partyId}).select('_id').lean();
+
+    if (!member) {
+      delete questMembers[memberId];
+    }
+  });
+
   if (userIsParticipating) {
     user.party.quest.key = this.quest.key;
     user.party.quest.progress.down = 0;