Next Wednesday, April 30, Criminal Minds is all-new on CBS. As the hit series gets ready to return from its hiatus, the Behavioral Analysis Unit (BAU) gears up to investigate a killer who poisons victims by using arsenic, and also writes death threats to those already deceased. Meanwhile, Supervisory Special Agent Aaron Hotchner (SSA Hotch) grows concerned over a more personal matter.

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Criminal Minds has taken a break from the CBS airwaves since its last installment, What Happens In Mecklinburg..., aired on April 9. On that episode, some of SSA Derek Morgan's (Shemar Moore) at-home issues were aired out, while the BAU investigated a series of kidnappings near Memphis, TN.

Likewise, on the upcoming episode 22, Fatal, the BAU investigates an unknown subject (UnSub) who appears to be infatuated with Greek mythology. What's more, SSA Hotch holds reservations about participating in career day at his third-grade son Jack's school, and must determine whether or not he will attend.

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A synopsis for Fatal reads: "Victims of arsenic poisoning are found in Long Beach. The investigation reveals that the killer has a fascination with Greek mythology, based on handwritten death threats to the deceased and other mysterious clues. Meanwhile, Hotch becomes concerned about participating in Jack's third-grade career day."

Catch Fatal on Wednesday, April 30 at 9 p.m. on CBS! Plus, check out a promo clip here: