ABC will air Season 4 episode 15 of "Switched at Birth" on Monday, 21 September. "Instead of Damning the Darkness, it's Better to Light a Little Lantern" will follow Travis, Bay and Daphne to rural Mexico, where they are spending their spring break volunteering. However, things get complicated when an unwanted guest arrives.

Daphne (Katie Leclerc), who was supposed to spend her spring break with boyfriend Mingo (Adam Hagenbuch) changed her plans at the last minute and decided to join the group of volunteers, who will distribute hearing aids to those in need in rural Mexico. However, the trip may cost Daphne her relationship itself as she is seen kissing a fellow volunteer in the promo for episode 14.

Read More: Bay Pregnant with Tank's Baby?

It is ironic as everyone had assumed that Mingo's playboy ways would be what ruins their relationship. Almost all her friends behaved rudely because of his reputation, but as it turns out Daphne cheats on Mingo.

Meanwhile, her sister Bay (Vanessa Marano) -- who is recovering from her break-up with Emmett (Sean Beardy) -- is going on the trip too. She has found a great friend in Travis (Ryan Lane), who knows exactly what she is going through, in more ways than one. She is finally in a happy place because her art is also being recognised, but everything goes haywire when Emmett comes on the trip, without any forewarning.

Read More: Mingo Surprises Daphne; Bay Starts Dating Travis?

Bay is unable to control her emotions and in a fit of anger tries to make her ex-boyfriend jealous by kissing his best friend Travis. A furious Emmett is seen punching Travis, who retaliates while a helpless Bay asks them stop.

Watch out for Season 4 episode 15 of "Switched at Birth" at 8.00 pm (EST) on Monday, 21 September, on ABC. You can also live stream "Instead of Damning the Darkness, it's Better to Light a Little Lantern" via ABC Go.

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