Poison - Inspiration for our thriller

Breaking Bad is television series that comes under the genre of thriller. We introduced poison as our method of killing the protagonist using inspiration from Breaking Bad. It is a US series that follows the plot of a chemistry teacher, Walter White, who turns to cooking crystal meth with a former student after being diagnosed with cancer. He uses ricin in attempts to poison and kill rivals.  Originally we weren't going to show how our character dies but we then thought poison would be the most suitable and subtle way. There isn't any other way for it to be realistic other than the 'killer' to enter her house and poison her drink. However, we make it evident to the audience she wont be aware that she is drinking poison until the killer calls her and exclaims 'you shouldn't have drunk that'. The poison we will use will be green (fairy liquid as it bubbles also) as red looks too much like blood and green is obvious as poison. it will be shown through a zoom out shot of the cup revealing the green, bubbling poison that sits at the bottom of the cup which our character is unaware of hence why she drinks it.

Ricin used as poison in Breaking Bad.

Green poison similar to what we will use in the cup