Heartache by the Number

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

Synopsis
Rose of Sharon Cassidy came to the Mojave with her caravan, but that dream has fallen through, run out of business by her competitors.

Walkthrough

 * 1) Begin You Can Depend on Me and continue that quest until given the task of convincing Cass to part with Cassidy Caravans.
 * 2) Return to Cass and convince her to part with the title for Cassidy Caravans.
 * 3) With a Barter of 50, the Courier can choose to sweeten the deal by throwing in an extra 750 caps.
 * 4) With a Barter of 75, the Courier can challenge her to a drinking contest. This requires 12 bottles of whiskeys and return to Cass.
 * 5) With a Speech of 50, the Courier can suggest that the Outpost is a pretty terrible place to be trapped. Cass will agree, but will point out that Ranger Jackson won't let her leave. Complete the quest Can You Find it in Your Heart? or kill Jackson to get her to leave.
 * 6) With a Speech of 75, the Courier can just challenge her by telling her she's responsible for the destruction of her caravan, and she'll reluctantly agree.
 * 7) Ask Cass to join you.
 * 8) Talk to her about what she wants to do next.
 * 9) Pay your respects with Cass at her caravan's grave.
 * 10) Investigate the wreckage of the Griffin Wares Caravan with Cass.
 * 11) Track down Durable Dunn's missing caravan with Cass.
 * 12) Deal with the Crimson Caravan and the Van Graffs. Cass will want to kill McLafferty and Van Graff,
 * 13) Option: Investigate Crimson Caravans and the Silver Rush for criminal evidence. These pieces of evidence are in the safes in the offices of the Crimson Caravan company (Crimson Caravan - Van Graff agreement) and the Silver Rush (Letter to Gloria). Take the evidence of the Caravan attacks to Jackson at the Mojave Outpost.
 * 14) Option: Assassinate Alice McLafferty and Gloria Van Graff by any means.

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 and also on Mojave Music Radio.

Bugs

 * 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 does talk to Cass this quest will begin abruptly with the "Clear the roads for Jackson..." and "(Optional) "Remove" Jackson as an obstacle..." completed, and no suggested next step.
 * 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.
 * It is possible to finish the quest peacefully, then also kill both targets. Cass will gain the Hand of Vengeance perk and end up with both perks. (Note that the GECK scripts appear to take away the Calm Heart perk when the Hand of Vengeance perk is granted, but it appears that companion perks are handled specially - in-game testing shows that she keeps both perks.)
 * 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.
 * After getting the evidence at the Silver Rush (Note To Gloria), it may not say that you have completed the objective. However, you can still give the evidence to Ranger Jackson at the Mojave Outpost and complete the quest that way.
 * The quest can be stuck if you finish There Stands the Grass first and side with Keely about deleting the data. There will be only one dialogue option and it's only saying goodbye.
 * After taking Cass to any caravan wreckage or other location that triggers a conversation she may stop following the player and become passive.
 * Sometimes the quest can stall after you get Cass to sell her caravan and the next step will not be viewable. There will also be no quest arrow on your map; recruiting Cass will fix the problem.
 * Despite being dismissed, Cass may appear in the Crimson Caravan office when the player enters and kill McLafferty.
 * The quest may halt after turning the evidence into Jackson. The quest doesn't get completed, and Cass doesn't get the perk.
 * The quest can be stuck if you first completed Young Hearts and convinced McLafferty to pay Janet. When you go to the Crimson Caravan to ask for work, the dialogue option will not appear.