Heartache by the Number

 is a quest in Fallout: New Vegas.

Objectives

 * Cass is drowning her sorrows at the Mojave Outpost. Her advice? Go work for the Crimson Caravan.
 * Pitch in at the Crimson Caravan company if you're looking for caravan work.
 * Convince Henry Jamison to quit his position at the Crimson Caravan company
 * Negotiate with Cass to buy out Cassidy Caravans for the Crimson Caravan company
 * (Optional) Acquire the Gun Runner's secret manufacturing specifications from their laboratory

Quick walkthrough

 * Talk to Alice McLafferty in the Crimson Caravan main Office, ask for work. If you have begun You Can Depend on Me and have not yet spoken to Hildern, you can proceed directly to him without seeing McLafferty first.
 * After telling you there's no caravan work, she'll ask you to deliver a holotape to Doctor Thomas Hildern.
 * Find him inside the Terminal at Camp McCarran, just east of New Vegas. He will tell you to return to Alice.
 * Return to Alice McLafferty and let her know you've delivered the invoice.
 * Return to Cass and see if you can get her to part with the title for Cassidy Caravans.
 * Pay your respects with Cass at her caravan's grave.
 * Investigate the wreckage of the Griffin Wares caravan with Cass.
 * Track down Durable Dunn's missing caravan with Cass.
 * Cass will give you two options for the next part of the quest:
 * Find evidence to incriminate Crimson Caravans and the Van Graffs
 * Option: Investigate the Crimson Caravan for reasons behind the attack. The evidence is located inside a locked safe in McLafferty's office, next to her desk.
 * Option: Assassinate McLafferty
 * Kill Alice McLafferty and Gloria Van Graff
 * Option: Investigate the Silver Rush in Freeside for evidence on the Van Graffs' guilt. The evidence is located inside a Hard locked safe behind a Hard locked door. There is also a Hard computer terminal to unlock the safe.
 * Option b) Assassinate Gloria Van Graff
 * Option: Take the evidence of the Caravan attacks to Jackson at the Mojave Outpost.
 * Option: Cass will gloat about the joy of killing her enemies, simply hear her out and the quest is over.

When the questline is completed, Cass will receive the Calm Heart perk or the Hand of Vengeance perk. Calm Heart gives Cass +50 HP, while Hand of Vengeance gives Cass a damage boost with Guns (confirmed, (15%, unsure)

Detailed Walkthrough
After Cass Asks the player to find the reasons for the attacks on her caravans, there are two options for completing the quest:

Peaceful Solution
This way is perhaps the more complicated route, but it does very little to decrease your Karma and in the NCR's case does much more positive than negative.


 * Start by going to the Silver Rush Casino without Cass, as having her as a companion will trigger aggression from the Van Graffs. Instead, have her wait outside and pickpocket the door man for the office key. Go inside, either using a Stealth Boy or with a high sneak rating to get inside the back office.


 * Enter the Van Graff's safe (requires 75 lockpick) and retrieve the note. Leave the Silver Rush. If you're feeling daring, you can go upstairs and lockpick the door to the room at the end of the hall on the left for some basic van graff style weaponry (plasma rifle, some ammo).


 * Go to the Crimson Caravan Camp, and while sneaking/stealthing enter Alice's office, lockpick her safe to retrieve the second note. Do this well and you shouldn't have to be violent with anyone.


 * Once you have both notes, take them to Ranger Jackson at the Mojave Outpost. After giving him the news of the conspiracy, speak to Cass and the quest will be completed, earning you 500xp and the Calm Heart perk - which gives her a +50 permanent health bonus (warning! may be bugged - see Calm Heart page for info).

Violent Solution
The Van Graffs are heavily armed and have good armor. Going into the Silver Rush and winning the ensuing gun battle may be very difficult.

A stealth boy can be used to great effect here.

However, if the Courier kills Simon first, four of the Van Graff thugs will come outside to do battle with the courier. By using a weapon such as a sniper rifle, they can be eliminated without too much difficulty. Upon entering the building, the Courier will be faced by one thug, Jean-Baptiste Cutting, and Gloria Van Graff. If the Courier takes out Cutting first, then the other two are relatively easy to dispose of.

It is also possible to kill all of the Van Graffs inside the shop by killing Jean-Baptiste Cutting first, and then standing behind Gloria Van Graff to keep the thugs from firing on you. They will all run behind the counter to try to take a shot at you and you can kill them one at a time.

an extremely easy way to kill the Van Graffs is to ask Gloria for a job. When you are given the job of guard at the door, allow the customer with the merchant outfit to enter without checking him and he'll blow the place with a powerful explosive, killing everyone inside. Cass will react just as if you killed the Van graffs yourself.

Bugs

 * If the PC accepts Can You Find it in Your Heart? and You Can Depend on Me before talking to Cass this quest will glitch so that the PC has "Clear the roads for Jackson..." and "(Optional) "Remove" Jackson as an obstacle..." completed and cannot progress any further.Solution Needed (PS3 and Xbox 360 Confirmed)
 * Solution: If she becomes your follower, just use the Talk To option and she will ask to go pay her respects at her caravan's grave. (PC,Xbox 360 and PS3 Confirmed)
 * Alternative Solution: If you previously killed the Van Graffs for the Brotherhood of Steel, but still want to finish the quest in peaceful way (and to obtain Calm Heart Perk for Cass), get both pieces of contract from VanGraffs and McLafferty, then bring the proof to Ranger Jackson, the quest will be completed after you speak to Cass.
 * Alternative Solution: Further to the situation described by the alternative solution noted above for the PC, it's worth noting that the quest log within the Pip-Boy will still show the waypoint to complete the quest as "Settling the score" with Alice McLafferty. If this happens, killing McLafferty will not end the quest, you will gain Infamy with the NCR - there will be no dialogue option to end the quest either before shooting her. The trick is to take the affore mentioned evidence to Ranger Jackson at the Mojave Outpost and the quest will end granting the Calm Heart Perk to Cass.


 * The continuity of this quest will be very confusing if you previously killed the Van Graffs for the Brotherhood of Steel or for other reasons. Upon first meeting Cass, she will tell you that she's glad the Van Graffs have been dealt with and that all that's left is to kill McLafferty.  The game will trigger the "Kill McLafferty" leg of the quest, even though neither you, nor Cass herself, have any idea why she should be killed.
 * A glitch is involved due to the above event. If action is taken upon the Van Graffs before the quest, then the murder of McLafferty will not end the quest, nor change options. It will appear to be uncompleteable since the marker is still shown at her body. However, after a longer wait you can talk to Cass, thus ending the quest.
 * Jean-Baptiste may have holstered his rifle meaning he does not shoot Cass, just stares her in the face. If this happens, kill cass outside of the silver rush before talking to him. NOTE: You may need to be on hardcore to kill this companion so a brief setting change may be necessary.
 * There is a glitch when trying to give the package to Hildern if you have already completed the There Stands the Grass quest. He will not open a dialogue option for handing him the package meaning you can't finish the quest.


 * When accessing the Van Graffs safe and terminal the graphics didn't show up but the noise was made for each. A way around this is to try the safe and use the vibrations of the controller to determine if the bobby pin is in the right area.


 * If you enter the Silver Rush and leave before the scene between the Van Graffs and the individuals that owe them money is complete the characters will remain frozen when you return. If you are trying to gather evidence against McLafferty and the Van Graffs, this will leave you unable to enter the Silver Rush to find the evidence without triggering them to attack you.


 * Upon choosing to "find evidence" for cass, then killing the Van Graffs anyway, recieving the note in the Van Graffs' safe does not let the courier finish the quest through a non-violent manner. The Courier can still give the evidence to Major Jackson, although this yields nothing. The only way to complete the quest is to Kill Alice too.


 * While attempting to complete non violently, and bringing Cass to see Jean-Baptiste he will attempt to kill her. If you tell him he will be sorry, they turn hostile towards you. If the courier and Cass survive the ensuing fight the letter will not be in the safe, and the terminal will not be accessible. Not sure what causes this. The only way to complete is to kill McLafferty.


 * If you kill the Van Graffs by bringing Cass to see Jean-Baptiste (And locking yourself into the "kill" chain) it seems you can kill McLafferty by simply taking Cass in your party to see McLafferty, then "releasing" Cass. As soon as she is released, she guns down McLafferty, none of the NPC's fire on her, or you. She then opens a dialog with you, talks the end of the quest through, then continues walking off back to her waiting point. No Karma is lost


 * There appears to be a bug by which the quest cannot be completed if you tell Cass to wait while attempting to sneak around to recover quest evidence. Presenting the evidence to Jackson does not resolve the quest, although this may be because Cass isn't around to talk to (she appears to have not reliably default to the starting location (Mojave) or Lucky 38 like most other followers)


 * (Possible Occurrence)After taking Cass to her caravan wreckage she will tell you to go to the next caravan site, but she will then stop following you and cannot be reacquired.(Tested on Xbox 360 and PS3)


 * When I killed the Van Graffs by bringing Cass to see Jean-Baptiste, I got locked out of the Las Vegas strip and the Lucky 38. The North Gate to the Las Vegas strip says you need a key to pass the gate.

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 broadcast in-game on Radio New Vegas.