When Mycroft returns on Elementary, he brings back not only a recently single heart but a confidence that Joan Watson will be his mate. When he offers her a possible relationship, Joan can't help but worry that she'll be teased by Holmes.

After Sherlock and Joan are asked to find a missing woman, they uncover not only one body but two and they are lead through the world of unmanned aeronautics.

As Joan ponders Mycroft's offer, Holmes wonders if he truly appreciates Watson for more than just selfish reasons.

While Sherlock investigates French mafia in his brother restaurant, the Brownstone is infiltrated by surveillance mosquitos.

With a shocking twist and a cliffhanger surely to keep you on the edge of your set, be sure you watch Elementary online to see it all unfold.

Watch Elementary Season 2 Episode 21 Online