Find out how one person quantifies a person’s worth in our Elementary season 3, episode 15, “When Your Number’s Up,” recap.

How do you solve a problem like a procedural? This is notElementary‘s first time flipping the script and putting the audience to work. When Detective Bell was shot in season 2, “Tremors,” the story unfolded through a series of recollections given by Sherlock on a disciplinary trial. Mixed with the present day situation of Bell’s health and Joan and Sherlock’s jobs on the line, the audience was actively engaged, looking for what could make two cases add up to Sherlock’s current predicament.

This week’s Elementary season 3, episode 15 embraces a difference format, but calls upon the audience once more. Within the first three minutes of the episode, not only do we know the killer, but also that compensation for death is one of her motivators. With the “Who” and a small piece of the “Why” pinned to our crime boards, the rest of the episode unfolds.

While we are half a step ahead of Sherlock in terms of identification, we are equally in the dark about two things, how to handle Watson’s return to the brownstone and what connection the killer has to victim reimbursement.

Let’s start with the latter. Dana, as she is later known, kills a homeless man leaving $3,814.62 on his body with a note giving the formula to calculate someone’s worth and the sentiment that life simply isn’t fair. The homeless man’s identity leads them to the offices of a victim’s compensation attorney Arlen Schrader. Lining up behind Sherlock Holmes, Schrader’s enemies are numerous.

A chat with Schrader’s ex-lover proves to be more fruitful and leads to the focus of the episode, a large pending payout from AceWay Airlines after a passenger flight to Vermont crashed leaving 81 dead. While Joan and Sherlock sift through hate mail, Dana is on to her next victim from a grief support group. Seducing the victim after a grief support meeting, Dana makes quick with payout, in the $80,000 range, deducting for his smoking habits. A second victim with connection to airline payout opens up the families of 79 other victims to danger.

The airline counsel for AceWay explain the process of their settlement team’s actions. If a formula similar to Schrader’s was used for the passengers’ families to be compensated, they could be looking at paying eight first class members $10-15 million and 67 coach passengers roughly a few hundred thousand each. Alternatively, if the formula disappears, and they settle on a flat sum, every passenger gets $5 million. The airline, clearly, would rather payout based on income and life expectancy. Money is a dirty business.

More pressing money matters come into play when Dana’s sister shows up to address Dana’s impending foreclosure. Dana chooses not to worry and pushes up her impending payout, framing herself as the next AceWay killer’s victim.

It almost comes as a relief to find that Sherlock catches onto Dana’s game earlier than the final five minutes of the episode. With all the pieces laid out in front of him, a few stray observations here and there, the show puts you on the clock with 15 minutes left to reach the conclusion Sherlock will undoubtedly reach by the time the credits roll.

Sherlock and the audience are looking at the same clues, but from different angles. Footprints in the backyard all point to the owner of the gun that Sherlock and Joan have traced. Dana must have known to use shoes to create the appearance of a limp to match the buyer. But a fatal flaw comes into play by with her choice of footwear staging. Her husband stood to bring in millions from the first class payout. So why does Dana take her story to the media demanding a payout of only $5 million?

Before we solve one mystery, let’s look at another. Watson’s apartment move was taken care of by Sherlock and his trusted one man mover. She turns down Sherlock’s offer to store her belongings in the basement of the brownstone, opting to give them, and the life she thought she could have, away. But the alternative she thought she was returning to is not there either. Once in the brownstone, Sherlock vacates to the basement, finally concerned for the first time that his behavior reflects that of a considerate housemate.

Watson’s final walk through of her Chelsea abode reveals that the next tenant is taking care of a few security issues, including the installation of an unpickable lock. Joan takes this and the basement as a hint that her presence is not welcome in the brownstone. That is far from the truth. In fact, as many fans can already guess, Sherlock and their work benefit greatly from Joan’s presence. Sherlock looks at this drastic move as a regression on Joan’s part.

His words are finally not being met with a valid rebuttal and the fact that they now hold truth for her puts him in the position of enabling. Sherlock realizes he needs to tread lightly. Keeping the apartment for Joan to return to, if she needed to, was his way of putting a stopper in the door to her freedom.

One major question remains for both the audience and the detectives, why go to the lengths of killing two people to collect a sum far less than her husband is worth? It turns out that calculated risk is not just something Sherlock was thinking of with Joan. Dana Powell’s husband became a frequent flyer following the diagnosis of an aggressive brain tumor. Vermont was his ticket to a doctor assisted suicide and Dana’s payout would be far less had his condition been taken into consideration in the settlement.

Aside from some cobwebs and a few hidden experiments here and there, Joan seals off the basement from the rest of the brownstone and creates her own sanctum sanctorum, much to the pleasure of Sherlock.

Elementary season 3, episode 16, “For All You Know,” returns on Thursday, March 6 at 10:00 p.m. ET on CBS.