diff --git a/addons/api/addon/adapters/host-set.js b/addons/api/addon/adapters/host-set.js
index fbbe11495..fe35a1935 100644
--- a/addons/api/addon/adapters/host-set.js
+++ b/addons/api/addon/adapters/host-set.js
@@ -7,32 +7,12 @@ export default class HostSetAdapter extends ApplicationAdapter {
 
   @service store;
 
-  // =methods
+  // =attributes
 
   /**
-   * Append a host catalog URL ahead of the host sets path if `hostCatalogID` is
-   * passed via adapter options.  Otherwise, generate the prefix as normal.
-   *
-   * TODO:  generalize the interface to resource-prefixed URLs by accepting
-   *        a modelName and an ID, rather than looking for a known key.
-   *
+   * Host catalogs use the new, unprefixed pathing style.
    * @override
-   * @param {string} path
-   * @param {string} parentURL
-   * @param {string} modelName
-   * @param {string} id
-   * @param {object} snapshot
-   * @return {string} urlPrefix
    */
-  urlPrefix(path, parentURL, modelName, id, snapshot) {
-    const hostCatalogID = snapshot?.adapterOptions?.hostCatalogID;
-    if (hostCatalogID) {
-      const hostCatalogAdapter = this.store.adapterFor('host-catalog');
-      return hostCatalogAdapter
-        ._buildPrefixedURL('host-catalog', hostCatalogID, snapshot);
-    } else {
-      return super.urlPrefix(...arguments);
-    }
-  }
+  hasScopePrefix = false;
 
 }
diff --git a/addons/api/addon/serializers/host-set.js b/addons/api/addon/serializers/host-set.js
index 3ce7c7161..697e7748d 100644
--- a/addons/api/addon/serializers/host-set.js
+++ b/addons/api/addon/serializers/host-set.js
@@ -2,6 +2,14 @@ import ApplicationSerializer from './application';
 
 export default class HostSetSerializer extends ApplicationSerializer {
 
+  // =attributes
+
+  /**
+   * Serialized the scope ID into the `scope_id` field.
+   * @type {boolean}
+   */
+  serializeScopeID = true;
+  
   // =methods
 
   /**
diff --git a/addons/api/tests/unit/adapters/host-set-test.js b/addons/api/tests/unit/adapters/host-set-test.js
index 9071a703a..1ab6f7a63 100644
--- a/addons/api/tests/unit/adapters/host-set-test.js
+++ b/addons/api/tests/unit/adapters/host-set-test.js
@@ -6,23 +6,17 @@ module('Unit | Adapter | host set', function(hooks) {
 
   test('it generates correct complete URLs', function (assert) {
     assert.expect(2);
-    const scopeID = 'o_1';
     const hostCatalogID = 'hc_098';
     const method = 'my-custom-method';
-    const mockSnapshot = {
-      adapterOptions: {
-        scopeID,
-        method
-      }
-    };
+    const mockSnapshot = { adapterOptions: { method } };
     const adapter = this.owner.lookup('adapter:host-set');
     // Without hostCatalogID...
     let url = adapter.buildURL('host-set', null, mockSnapshot, 'findAll');
-    assert.equal(url, '/v1/scopes/o_1/host-sets:my-custom-method');
+    assert.equal(url, '/v1/host-sets:my-custom-method');
     // With hostCatalogID...
     mockSnapshot.adapterOptions.hostCatalogID = hostCatalogID;
     url = adapter.buildURL('host-set', null, mockSnapshot, 'findAll');
-    assert.equal(url, '/v1/host-catalogs/hc_098/host-sets:my-custom-method');
+    assert.equal(url, '/v1/host-sets:my-custom-method');
   });
 
 });
diff --git a/ui/core/app/routes/scopes/scope/projects/project/host-catalogs/host-catalog/host-sets.js b/ui/core/app/routes/scopes/scope/projects/project/host-catalogs/host-catalog/host-sets.js
index 4fbec613f..045a0f632 100644
--- a/ui/core/app/routes/scopes/scope/projects/project/host-catalogs/host-catalog/host-sets.js
+++ b/ui/core/app/routes/scopes/scope/projects/project/host-catalogs/host-catalog/host-sets.js
@@ -8,19 +8,6 @@ export default class ScopesScopeProjectsProjectHostCatalogsHostCatalogHostSetsRo
   @service intl;
   @service notify;
 
-  // =attributes
-
-  /**
-   * Configure adapter options using current host catalog and
-   * the current project scope.
-   * @return {object}
-   */
-  get adapterOptions() {
-    const scopeID = this.modelFor('scopes.scope.projects.project').id;
-    const hostCatalogID = this.modelFor('scopes.scope.projects.project.host-catalogs.host-catalog').id;
-    return { adapterOptions : { scopeID, hostCatalogID } };
-  }
-
   // =methods
 
   /**
@@ -29,7 +16,9 @@ export default class ScopesScopeProjectsProjectHostCatalogsHostCatalogHostSetsRo
    */
   async model() {
     this.store.unloadAll('host-set');
-    return this.store.findAll('host-set', this.adapterOptions);
+    const { id: host_catalog_id } =
+      this.modelFor('scopes.scope.projects.project.host-catalogs.host-catalog');
+    return this.store.query('host-set', { host_catalog_id });
   }
 
   // =actions
@@ -54,7 +43,7 @@ export default class ScopesScopeProjectsProjectHostCatalogsHostCatalogHostSetsRo
   async save(hostSet) {
     try {
       const { isNew } = hostSet;
-      await hostSet.save(this.adapterOptions);
+      await hostSet.save();
       this.notify.success(
         this.intl.t(isNew ? 'notify.create-success' : 'notify.save-success')
       );
@@ -72,7 +61,7 @@ export default class ScopesScopeProjectsProjectHostCatalogsHostCatalogHostSetsRo
   @action
   async delete(hostSet) {
     try {
-      await hostSet.destroyRecord(this.adapterOptions);
+      await hostSet.destroyRecord();
       this.notify.success(this.intl.t('notify.delete-success'));
       this.transitionTo('scopes.scope.projects.project.host-catalogs.host-catalog.host-sets');
     } catch (error) {
diff --git a/ui/core/app/routes/scopes/scope/projects/project/host-catalogs/host-catalog/host-sets/host-set.js b/ui/core/app/routes/scopes/scope/projects/project/host-catalogs/host-catalog/host-sets/host-set.js
index 4c98b45f2..7b422c1ac 100644
--- a/ui/core/app/routes/scopes/scope/projects/project/host-catalogs/host-catalog/host-sets/host-set.js
+++ b/ui/core/app/routes/scopes/scope/projects/project/host-catalogs/host-catalog/host-sets/host-set.js
@@ -10,12 +10,7 @@ export default class ScopesScopeProjectsProjectHostCatalogsHostCatalogHostSetsHo
    * @return {HostSetModel}
    */
   async model({ host_set_id }) {
-    const { id: scopeID } = this.modelFor('scopes.scope.projects.project');
-    const hostCatalogID = this.modelFor('scopes.scope.projects.project.host-catalogs.host-catalog').id;
-    return this.store.findRecord('host-set', host_set_id, {
-      reload: true,
-      adapterOptions: { scopeID, hostCatalogID }
-    });
+    return this.store.findRecord('host-set', host_set_id, { reload: true });
   }
 
   /**
diff --git a/ui/core/app/routes/scopes/scope/projects/project/targets/target/add-host-sets.js b/ui/core/app/routes/scopes/scope/projects/project/targets/target/add-host-sets.js
index d7723d4f0..96e1cd71a 100644
--- a/ui/core/app/routes/scopes/scope/projects/project/targets/target/add-host-sets.js
+++ b/ui/core/app/routes/scopes/scope/projects/project/targets/target/add-host-sets.js
@@ -26,12 +26,10 @@ export default class ScopesScopeProjectsProjectTargetsTargetAddHostSetsRoute ext
   async model() {
     const target =
       this.modelFor('scopes.scope.projects.project.targets.target');
-    const { scopeID } = target;
     const { id: scope_id } = this.modelFor('scopes.scope.projects.project');
     const hostCatalogs = await this.store.query('host-catalog', { scope_id });
-    await all(hostCatalogs.map(({ id: hostCatalogID }) =>
-      this.store
-        .findAll('host-set', { adapterOptions: { scopeID, hostCatalogID } })
+    await all(hostCatalogs.map(({ id: host_catalog_id }) =>
+      this.store.query('host-set', { host_catalog_id })
     ));
     const hostSets = this.store.peekAll('host-set');
     return {
diff --git a/ui/core/mirage/config.js b/ui/core/mirage/config.js
index 828c3f971..7c7a1fdf8 100644
--- a/ui/core/mirage/config.js
+++ b/ui/core/mirage/config.js
@@ -171,18 +171,14 @@ export default function() {
 
   // host-set
 
-  this.get('/host-catalogs/:hostCatalogId/host-sets', function ({ hostSets }, { params: { hostCatalogId } }) {
+  this.get('/host-sets', function ({ hostSets }, { queryParams: { host_catalog_id: hostCatalogId } }) {
     return hostSets.where({ hostCatalogId });
   });
-  this.post('/host-catalogs/:hostCatalogId/host-sets', function ({ hostSets }, { params: { hostCatalogId } }) {
-    const attrs = this.normalizedRequestAttrs();
-    attrs.hostCatalogId = hostCatalogId;
-    return hostSets.create(attrs);
-  });
-  this.get('/host-catalogs/:hostCatalogId/host-sets/:id');
-  this.patch('/host-catalogs/:hostCatalogId/host-sets/:id');
-  this.del('/host-catalogs/:hostCatalogId/host-sets/:id');
-  this.post('/host-catalogs/:hostCatalogId/host-sets/:idMethod', function ({ hostSets }, { params: { idMethod } }) {
+  this.post('/host-sets');
+  this.get('/host-sets/:id');
+  this.patch('/host-sets/:id');
+  this.del('/host-sets/:id');
+  this.post('/host-sets/:idMethod', function ({ hostSets }, { params: { idMethod } }) {
     const attrs = this.normalizedRequestAttrs();
     const id = idMethod.split(':')[0];
     const method = idMethod.split(':')[1];
diff --git a/ui/core/mirage/factories/host-catalog.js b/ui/core/mirage/factories/host-catalog.js
index 15ae0bb26..f2541fcb7 100644
--- a/ui/core/mirage/factories/host-catalog.js
+++ b/ui/core/mirage/factories/host-catalog.js
@@ -5,10 +5,10 @@ export default factory.extend({
 
   withChildren: trait({
     afterCreate(hostCatalog, server) {
-      const scope = hostCatalog.scope;
+      const { scope } = hostCatalog;
       const scopePojo = { id: scope.id, type: scope.type };
       const hosts = server.createList('host', 10, { scope: scopePojo, hostCatalog });
-      server.createList('host-set', 3, { scope: scopePojo, hostCatalog, hosts });
+      server.createList('host-set', 3, { scope, hostCatalog, hosts });
     }
   })
 
diff --git a/ui/core/mirage/factories/target.js b/ui/core/mirage/factories/target.js
index 7c74806a6..a96e15556 100644
--- a/ui/core/mirage/factories/target.js
+++ b/ui/core/mirage/factories/target.js
@@ -13,7 +13,12 @@ export default factory.extend({
     afterCreate(target, server) {
       let randomlySelectedHostSets;
       randomlySelectedHostSets = server.schema.hostSets
-        .where(item => item.scope.id === target.scope.id).models
+        // BLERG:  fun fact, for no reason at all, the element passed
+        // into a where function is not a full model instance, as you might
+        // expect at this level of abstraction, but appears to be a serialized
+        // representation of the model instance.  It's very confusing since
+        // the result set of `where` _is a collection of model instances_.
+        .where(hostSet => hostSet.scopeId === target.scope.id).models
         .filter(() => randomBoolean(hostSetChance));
       target.update({hostSets: randomlySelectedHostSets});
     }
diff --git a/ui/core/mirage/models/host-set.js b/ui/core/mirage/models/host-set.js
index 3aa8fbf7e..5a579e119 100644
--- a/ui/core/mirage/models/host-set.js
+++ b/ui/core/mirage/models/host-set.js
@@ -2,6 +2,7 @@ import { Model, belongsTo, hasMany } from 'ember-cli-mirage';
 
 export default Model.extend({
 
+  scope: belongsTo(),
   target: belongsTo(),
   hostCatalog: belongsTo(),
   hosts: hasMany()
diff --git a/ui/core/mirage/serializers/host-set.js b/ui/core/mirage/serializers/host-set.js
index bd680326e..16d665375 100644
--- a/ui/core/mirage/serializers/host-set.js
+++ b/ui/core/mirage/serializers/host-set.js
@@ -10,10 +10,20 @@ export default ApplicationSerializer.extend({
     )}_ids`;
   },
 
+  keyForRelationshipId(relationshipName) {
+    return `${this._container.inflector.singularize(
+      underscore(relationshipName)
+    )}_id`;
+  },
+
   _hashForModel(model) {
     const json = ApplicationSerializer.prototype._hashForModel.apply(this, arguments);
     json.host_ids = model.hostIds;
     json.host_catalog_id = model.hostCatalogId;
+    json.scope = {
+      id: model.scope.id,
+      type: model.scope.type
+    };
     return json;
   }