Heartache by the Number

Heartache by the Number is a companion quest in Fallout: New Vegas.

Persuading Cass
Upon first interaction with Cass, she will direct the Courier to the Crimson Caravan Company for work. Once there, Alice McLafferty, the company's manager, will assign a series of jobs. One of these jobs will involve buying off Cass's caravan, Cassidy Caravans. There are several methods of convincing her to give up her caravan:
 * With a Barter skill of 50, one can choose to sweeten the deal by throwing in an extra 750 caps.
 * With a Barter skill of 75, one can challenge her to a drinking contest. One will need to acquire twelve bottles of whiskey. (The dialogue will vary depending on one's Endurance and alcohol addiction status, but the outcome is always the same: she will agree to sell.)
 * With a Speech skill of 50, one can suggest that the outpost is a pretty terrible place to be trapped.
 * Cass will agree, but Ranger Jackson won't allow her to leave. The Courier can earn Jackson's agreement by performing the job he assigns.
 * With a Speech skill of 75, one can persuade her by telling her that she's responsible for the destruction of her caravan.

Notes:
 * There is a bug with There Stands the Grass that can lock up Thomas Hildern's dialogue preventing the completion of You Can Depend on Me and ultimately preventing the recruitment of Rose of Sharon Cassidy as a companion. Therefore it is highly recommended that the player complete this quest prior to There Stands the Grass.
 * These are the only possible methods of persuading her.
 * It is possible to get twice as much experience with multiple skill checks. For the first check, challenge Cass to a drinking competition and then instead of getting whiskey, choose one of the other options for the second check.

The Mystery of the Caravans
After Cass is persuaded, she can be recruited as a companion. If one has Evil Karma, she will not initiate the quest and will instead yell or even leave the party.

After talking to her (via the companion wheel) with sufficient Karma for her not to be annoyed, she will want to visit her caravan's wreckage site to pay her respects. Cass's caravan wreckage will have nothing left but a dead pack brahmin and some miscellaneous loot. Upon further examination, Cass will notice something suspicious and suggests visiting Griffin Wares' caravan.

The second caravan, which is found nearby a billboard south-west of the Horowitz farmstead has suffered the same fate as her caravan. Aside from the three dead pack brahmins and various scattered loot, there are three ash piles. Cass will become even more suspicious, and will want to examine Durable Dunn's caravan.

Durable Dunn's caravan, aside from the similar damage the earlier caravans sustained, has the corpses of a Van Graff thug and a Crimson Caravan guard. The picture will be clear to Cass; the Crimson Caravan Company and Silver Rush are colluding to eliminate competition for the caravan business. She wishes to kill Alice McLafferty, the Crimson Caravan manager, and Gloria Van Graff, the head merchant of the Silver Rush, for all of the damage they caused. One can intervene in Cass's rash decisions and offer a more peaceful solution, or agree and aid her in killing both of them. Attention: If this is done after the player has started Birds of a Feather with the Silver Rush faction, be aware there is a Silver Rush member near by. Killing him will cause the Silver Rush faction to be hostile towards the player upon returning to Freeside. When Simon begins to attack the player, the Birds of a Feather quest is failed.

Peaceful solution
To come up with a more peaceful solution, one must gather evidence of the two caravans' true motives. These pieces of evidence are located in the two following locations: a safe in the Crimson Caravan main office and a safe behind a locked room in the Silver Rush. If one agreed to help Cass "settle accounts" with Alice McLafferty and Van Graffs, there won't be any evidence in the safes if changing one's mind.

Crimson Caravan main office
The evidence required to prove Crimson Caravan's reasons for attacking is located in a safe in the main office, next to Alice McLafferty's desk. It can be unlocked in two possible ways, with a loss of karma:
 * Having a Lockpick skill of 50.
 * Unlocking the safe with McLafferty's safe key. It can be acquired by pickpocketing her.

Once the incriminating note has been obtained, talk to Cass and show her the evidence.

Silver Rush
The evidence required to prove the Van Graffs' true motives is located in a safe behind a locked door inside the store. There are two ways to open the door:
 * Unlocking it with a Lockpick skill of 75.
 * Using a key to unlock it, which is carried by all of the Van Graff members (except for the crier).

The safe can also be opened in two ways:
 * Unlocking it with a Lockpick skill of 75.
 * Disengaging the lock by hacking the terminal near it with a Science skill of 75.

Again, once the evidence has been obtained, talk to Cass and show her the evidence.

Cass's Calm Heart
Once the two pieces of evidence have been obtained, Cass will suggest taking it to Ranger Jackson. The evidence will be passed on to NCR higher-ups, determining the fate of the two companies.

The quest will end once one talks to Cass. Cass will receive the Calm Heart perk, which grants her an additional 50 HP. One will also receive 500 Experience Points.

Additional notes

 * Obtaining the evidence inside the Crimson Caravan main office will be easier at night, since the office will be empty. Alice will also be sleeping, making the key easier to pickpocket.
 * Jean-Baptiste Cutting, Silver Rush's second-in-command, can turn hostile after a period of time if he is in the same room as Cass.
 * Even if spotted lockpicking the door inside the Silver Rush, the Van Graffs won't become hostile, unless playing the Ultimate Edition.
 * As of patch 1.2, turning in the evidence will turn the Van Graffs permanently hostile.
 * Lockpicking all of the required safes and doors will incur negative Karma.

Violent solution
One can aid Cass's initial plan by helping her kill Alice McLafferty and Gloria Van Graff, by any means necessary. So long as both of the managers are dead, Cass will have fulfilled her vengeance.


 * There is a possible glitch to this. if one first kills the Van Graffs and have previously talked to Cass (one may also have to buy Cassidy Caravans for the You Can Depend On Me quest too), it automatically starts the Violent Solution. When one next talks to her she will want to kill Alice McLafferty next, entirely skipping the parts where one must search the destroyed caravans.
 * Another glitch involves killing Alice McLafferty with a silenced weapon to avoid the penalties to reputation or allowing a companion to get the finishing blow for the same reason. It is also possible to kill Alice and have the quest complete in these ways if Cass is present. Talking to Cass after killing Alice even though the quest did not update will finish the quest violently.

Cass's Hand of Vengeance
Once both targets are dead, speak to Cass to conclude the quest. Cass will earn the Hand of Vengeance perk, which gives her an additional 15% damage with guns. One will also receive 500 experience points.

Behind the scenes
This is one of many quests that are named after songs that can be heard on the radio, in this case the Guy Mitchell song Heartaches by the Number, which is broadcasted in-game on Radio New Vegas and Mojave Music Radio.

Bugs

 * Sometimes the quest can stall after you get Cass to sell her caravan. Aside from the next step being not viewable, the quest arrow will not appear.
 * Recruiting Cass will fix the problem.
 * If the player completes "Can You Find it in Your Heart?" and starts You Can Depend on Me before talking to Cass, when the player talks Cass, this quest will begin abruptly with the messages "Clear the roads for Jackson..." and "(Optional) 'Remove' Jackson as an obstacle..." completed, preventing the next step from appearing.
 * To fix this, continue the quest, get her to sell her caravan, and recruit her as a follower.
 * After taking Cass to any caravan wreckage or other location that triggers a conversation, she may stop following the player and become passive.
 * When attempting to get the evidence at Silver Rush, the terminal attached to the safe might not activate.
 * When traveling from the east gate of Crimson Caravan Company to Durable Dunn's sacked caravan, the quest marker may lead the player through Isaac's house.
 * Despite being dismissed, Cass may appear in the Crimson Caravan main office when the player enters and kills McLafferty.
 * After getting the evidence at the Silver Rush, it may not say that you have completed the objective. However, you can still give the evidence to Ranger Jackson in the Mojave Outpost and complete the quest that way.
 * The quest may halt after turning the evidence into Jackson. The quest doesn't get completed, and Cass doesn't get the perk.
 * Telling Cass to wait outside and then collecting the evidence from the Silver Rush causes Cass to disappear from her spot. She will still be shown on the world map, but not on the local map.
 * To fix this, go to one of the companion dismissal terminals and use it to dismiss Cass. She will then be automatically sent back to the Mojave Outpost, where you can re-hire her.
 * Cass may be found inside the Silver Rush if the Courier hasn't completed Birds of a Feather. When Gloria Van Graff tells the Courier to speak to Jean-baptiste he can be found in a back room with her and can also be stealth killed without alerting the rest of the room.
 * Cass can be knocked unconscious while fighting the Van Graffs inside their building. After killing them, Cass will not activate the conversation complaining the player has changed their mind.
 * The quest can be stuck if you finish There Stands the Grass first and side with Keely about deleting the data. There will only be one dialogue option (saying "Goodbye").
 * The quest can be stuck if you finish There Stands the Grass first and side with Keely about deleting the data. There will only be the first set of dialogue options when you talk to Cass, disabling you from picking the other dialogue options.
 * If the player kills Alice McLafferty and the Van Graffs before ever meeting Cass, Cass will initiate conversation as if you have talked to her before, recruiting her as a companion and giving her both of the perks. However, she will be unable to physically follow the player. Cassidy will be listed as a follower, but upon speaking to her again, she will speak to the player as if they have never met. Even though Ranger Jackson's quest is initiated (and completed), she will still not follow you.
 * After completing Oh My Papa by convincing the Great Khans to leave the Mojave, entering the Crimson Caravan main office at night will cause the Great Khans to attack the people inside, but will not be hostile to the player.
 * Completing the quest by killing the Van Graffs seems to cause the energy weapons to not show up in Vendortron's inventory if you have Gun Runners' Arsenal installed. Removing the add-on, killing Gloria Van Graff, then re-installing should fix this issue.
 * If you have killed the Van Graffs as part of the quest "Tend to Your Business" talking to Cass wil start this quest from the part where she asks you to kill Alice McLafferty, though you can still finish the quest peacefully, should you find the evidence and talk to Ranger Jackson.
 * Playing the Ultimate Edition, in Silver Rush and having activated both Birds of a Feather and Heartache By the Number plus reaching the point of making a permanent solution, when trying to pick the door leading to the safe, a firefight may ensue. Exiting Silver Rush after Gloria is killed and while Jean Baptiste is alive, will reveal is still Cass inside. Upon returning inside, all hostilities have ended and the Courier can choose to kill Cass. However, upon doing so, the Courier can not move in-game, despite menu functions working, probably due to Gloria being killed.