Concerned about the safety of a treehouse Calvin's building for Grover, Dave recruits Marty to supervise covertly. An innocent mistake on Malcolm's part leads to a heated bake-off between Tina and Gemma.
When Jay's sister comes to visit after being dumped by her boyfriend, they're shocked to discover that she's communicating with someone they know on a dating app.
When a wealthy couple are killed by a female con artist posing as a personal trainer, the team works to find out her true identity and track her down. Ortiz is put in a tough place when Hana's brother asks for a favor.