Former President Joe Biden and his son Hunter paid a surprise visit Monday morning to the "Reacher" Season 4 set in Philadelphia.

Ritchson shared an Instagram post of the chance encounter, writing, "So our Reacher set got in the way of these legends." Ritchson's post featured a carousel of photos and videos

The blockbuster action star shared a series of images of the impromptu meet-and-greet along with a joke that they discussed “string theory and quantum entanglement.”