When Henry Allen bid farewell at the start of "The Flash's" second season, viewers -- and Barry Allen -- wondered when he would make his return to Central City.

RELATED: "The Flash's" Grant Gustin Discusses Barry's Reaction to That Big Zoom Reveal

Now, star Grant Gustin has shared the first look as John Wesley Shipp's return with an enigmatic photo of Henry, seated in a cabin with an inscrutable look on his face. As Gustin puts it, "what the F is happening" in this photo?

At some point in the history of time, I sat across from this beautiful, kind & giving man that plays my father on television. That is when I took this picture. This moment will in fact be on television at some point. But when? And what the F is happening? Other than John Wesley Shipp looking GQ af. A photo posted by Grant Gustin (@grantgust) on

Though he's been out of sight, Henry Allen character was never gone from the minds of "Flash" fans. For a long time, he remained one of the leading choices for Zoom's alternate identity. While that theory has seemingly been disproved, there remains the question of where he's been while Team Flash has been tackling Earth-2 doppelgangers, and why he'll be returning.

"The Flash" returns Tuesday, March 22, at 8/7c on The CW.