We finally got a little more information about Special Agent Alex Quinn (Jennifer Esposito) on Tuesday's episode of NCIS.

Gibbs (Mark Harmon) sends Quinn and Bishop (Emily Wickersham) up to Philadelphia to investigate the murder of a sailor. Bishop can't wait to get her hands on some cheesesteaks, but it's clear from the get go that Quinn would rather be assigned pretty much anywhere else other than the City of Brotherly Love. Why?

Does it have anything to do with Tony Francis (Tony Gonzalez), who stops by headquarters at the beginning of the episode? We learn that he and Quinn had some sort of romantic dalliance a few years ago, and he's been trying to reconnect with her ever since, oblivious to the fact that she's very intentionally not returning his calls. Nah, it's more complicated than that.

NCIS Mega Buzz: What's the secret connection between Torres and Quinn?

In Philly, Bishop and Quinn link back up with Clayton Reeves (Duane Henry) from MI6, who makes his official return to the show as a new series regular. But during the course of the investigation, Quinn starts having unpleasant flashbacks and it soon becomes clear that she lost someone close to her when she was a field agent. When Bishop confronts her about her strange behavior, Quinn cryptically says that her previous time in Philly "didn't end well," and basically goes AWOL, prompting Gibbs to head north himself to see what's going on.

After finding Quinn drowning her sorrows in the hotel bar, Gibbs plays armchair psychologist and tells her he believes she sent him subpar agents to replace DiNozzo because she herself wanted to get back into the field. Twist! She initially denies it, but it's obvious that Gibbs is on to something.

Eventually, Quinn spills the beans that one night while she and her partner -- a Port Authority cop named Emily Shaw -- were on a stakeout while working on a Philly task force, Emily exited their police car and was shot at by some robbery suspects. Quinn couldn't get to her body in time before she succumbed to her wounds. Gibbs reminds Quinn that it wasn't her fault, that she and Shaw were ambushed, but Quinn confesses to what wasn't in the incident report: The reason Emily exited their car in the first place was to give Quinn privacy, as she was arguing with her then-fiancé over the phone. It was after that that Quinn left the field and became an instructor. And the fiancé quickly got out of the picture as well.

At Gibbs' urging, Quinn manages to heal some of her old wounds by going to visit Emily's widow and their son, who's now 13.

One interesting tidbit to note: While Quinn initially wants to avoid Philly like the plague, Torres (Wilmer Valderrama), on the other hand, is eager to get up there. Is it because he has a little crush on Bishop, or is there something deeper that links him to the city -- and perhaps to Quinn? Regardless, he and Abby (Pauley Perrette) seem to be forging a nice little bond back at headquarters.

NCIS airs Tuesdays at 8/7c on CBS.

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