[This article contains spoilers for The Flash 3x20 'I Know Who You Are']

As if Savitar wasn't enough of a villain to contend with, the penultimate episode of season three of The Flash – entitled Infantino Street – is set to see the return of two of the titular hero's most colourful adversaries: King Shark and Captain Cold.

In the recently-released trailer for the episode, fans see Barry Allen (Grant Gustin) enlist the help of not-so-bad baddie Leonard Snart (Wentworth Miller) in order to retrieve the power source that will enable physicist Tracy Brand and HR to operate their Savitar trap. The reason the Scarlet Speedster needs Cold's assistance? Well, it just so happens that the material required is being protected by none other than half-man, half-fish King Shark.

Almost the show's entire third season has revolved around Savitar and how, during an attempt to stop him, Barry accidentally ran five months into the future and witnessed the villain kill his love Iris West (Candice Patton). In a much more recent episode, it was revealed that Savitar is actually Future Barry himself after he was thrown into a murderous rage after losing Iris in the first place. Talk about time travel confusion!

The last time viewers saw King Shark, he was being carted off to an ARGUS prison facility by director of the organisation Lyla Michaels (Audrey Marie Anderson). Assuming that he's still residing there, it's questionable why Michaels would trust the murderous man-shark to act as a "guard-dog", protecting an immensely potent alien power source. But then again, who's to say King Shark didn't escape from ARGUS and take the power source with him?

Wentworth Miller as Captain Cold
Wentworth Miller plays Captain Cold The CW / YouTube

"The Flash, a thief? It's my kind of mission," Cold enthusiastically says when Barry approaches him with the task at hand in the new clip. "If we don't use this, Iris is going to die," Barry states as the severity of Team Flash's situation hits home.

The Flash 3x22 will air in the US on The CW on 16 May. The same episode will air in the UK on Sky 1 on the 23rd.