The Fosters 4×19 “Who Knows” Season 4 Episode 19 Sneak Peek – Everyone seems to be hiding something, but the secrets come spilling out, on an all-new episode of “The Fosters,” airing Tuesday, April 4th, on Freeform. It seems just about everyone in the Adams Foster household has a secret, but unfortunately for each of them, they all start spilling out. With Callie’s court date inching closer, Robert’s attorneys present a defense strategy that Callie vehemently opposes. Monte and Lena join forces to stop Drew’s underhanded dealings. Stef works to bust Diamond’s pimp. Jesus asks Gabe to keep a secret from his moms.