Patients flood the hospital after gunfire goes off at a parade; a blast from the past throws Maggie off her game on the same day that Meredith tries to talk to her about dating Deluca; Owen and Amelia get some potentially life-altering news.

A patient gives Meredith some clarity on her dating situation around the holidays. The strain on Bailey and Ben’s marriage comes to a head. Meanwhile, Betty drops a bomb on Owen and Amelia.

Amelia and Koracick tackle a daunting surgery on Catherine while Richard and Jackson hope for the best. Meanwhile, Richard urges Meredith to visit her father, Thatcher, before his time is up.

Meredith questions Link’s laid-back approach over a patient’s treatment. Maggie worries that Richard, Jackson and Catherine haven’t come to terms with Catherine’s diagnosis. Meanwhile, Deluca steps up in the O.R. when Owen faces a setback.

Meredith Grey and the team of doctors at Grey Sloan Memorial are faced with life-or-death decisions on a daily basis. They seek comfort from one another, and, at times, more than just friendship. Together they discover that neither medicine nor relationships can be defined in black and white.

One of Grey Sloan Memorial’s own is seriously injured, making the team reflect on what is truly important to them. Meanwhile, Nicole Herman pays a visit to Grey Sloan and talks to Arizona about an exciting opportunity.

Alex and Jo go on a road trip to Iowa to find Alex’s mom, whom he hasn’t heard from in a very long time. Meanwhile, Meredith gives a presentation on her mini-livers project, which attracts a ton of attention; and Jackson works to rebuild the foundation after its reputation is threatened.

The hospital brings in crisis management to help them sort out allegations against Harper Avery. Nurse Olivia shows up at Grey Sloan with her son, throwing Alex and Jo for a loop Arizona decides to spend more time with Sofia who is having a hard time at school.

During presentations on Grey Sloan Surgical Innovation Prototypes Day, Arizona shares cookies from an appreciative patient that, unbeknownst to her, contain a special ingredient. Meanwhile, Catherine reveals shocking details to Jackson about his grandfather's past; and Jo steps in mid-operation on a major surgery.

An agent from ICE shows up at Grey Sloan in search of an employee who may be working in the U.S. under DACA. Alex’s patient Kimmie wants to leave the hospital to enjoy her final days, but Alex feels differently. Meanwhile, Arizona treats Matthew Taylor’s baby and April wants to do whatever she can to help.