Marcella fans have lots of theories about the killer after episode seven's shock ending

The penultimate episode of Marcella series two left viewers scrambling to piece together disparate parts of the mystery after a shock ending revealed an unlikely antagonist.

**Spoilers for Marcella series two to follow**

• Meet the cast of Marcella series 2
• The real life disorder behind Marcella's black-outs

Throughout the series, London detective Marcella has been investigating a series of child murders, and in episode seven, she was led to the house of Nigel Stafford, who held her at knifepoint before revealing that his girlfriend Rosio was being kept captive by the murderer. This gave Marcella and her colleagues a direct line to the murderer who had been in contact with Nigel online. But an attempt to track him down led to Rosio's death.

Elsewhere, Marcella's son Edward popped round to visit his ex-girlfriend Samantha, only to be invited inside and poisoned by her mother Jane, who apparently suspected Edward of beating her daughter.

Many viewers took to Twitter to theorise as to what might be going on. Is Jane the killer? Is there a group of murderers? Why are Marcella's trousers so short? Users shared some elaborate answers on Twitter.

Check out the best ones below:

Marcella series 2 concludes next Monday at 9pm on ITV