“Chaos Theory” is episode seven of season three of Marvel’s Agents of S.H.I.E.L.D.
At the end of the previous episode, “Among Us Hide”, May and Bobbi had managed to find von Strucker before Ward’s people killed him. May managed to talk to him before he lapsed into a coma, and he told her exactly what happened in the store in “Devils You Know”, and how May’s former husband, Andrew, had turned into a monster.
This episode opens six months previously, when May and Andrew were in Hawaii. Andrew had opened one of Jiaying’s books and got infected by the mutagene. This is what turned him into Lash. May now knows that something is wrong with Andrew, but she doesn’t yet know he’s Lash. She hasn’t told anyone else yet, and goes looking for him.
Lincoln contacts Mack and tells the latter that Lash has to be inside S.H.I.E.L.D., and that he will be able to find out who it is. Coulson, who had been heading for a meeting with the president with Rosalind Price, turns the plane back. This episode is almost all about Lash.
Back at base, Fitz is listening to the recordings that Simmons made on her phone in “4,722 Hours”, and thinks he may have a way to re-open the portal. Nothing from Ward or HYDRA until the very end, when Ward meets up with Gideon Malick, possibly the last survivor of the former leaders of HYDRA, and one which all the others were afraid of.