TV tonight: 'Flash,' 'Agents of S.H.I.E.L.D.'

The Flash
CW, 8 ET/PT

In whatever multiverse incarnation he appears, our dear Dr. Wells (Tom Cavanagh) is just a magnet for trouble. This week, he’s captured by a bounty hunter — the visiting DC superhero Gypsy (guest star Jessica Camacho) — who plans to bring him back for trial to Earth-19, which bans inter-dimensional travel. (And after all the problems such travel has caused for The Flash, and viewers of The Flash, there might be some people willing to get behind the same ban on Earth-1.) It turns out the only way to keep Wells here is to challenge Gypsy to a fight to the death, which is just what Cisco has planned.

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American Experience: The Race Underground
PBS, 9 ET/PT (times may vary)

If you’ve ever wondered how subways were built, this always worthy history series examines the construction of the first system to open in America, in Boston. To build it, the engineers had to overcome incredible technological challenges, and fervent opposition from worried businesses and frightened potential riders. It's a reminder that such things can be done.

Marvel's Agents of S.H.I.E.L.D.
ABC, 10 ET/PT

Patton Oswalt is back in his dual role as Agents Sam and Billy Koenig, which is certainly an incentive to watch. This time, the Koenigs are in danger because they have the Darkhold book, and it's up to the Agents to save them.