Lily, Martha and Jas are smart but socially awkward girls trying to make sense of life, boys and fitting in. When Jas asks Lily what her first kiss with Matt was like Lily panics - there hasn't been a first kiss yet! It makes her doubt whether they are actually going out. The challenge is now on to kiss Matt to prove they really are boyfriend and girlfriend. Lily asks Matt to do a science project together, researching the history of heart transplants. She figures this will be an ideal topic to bring them together. Meanwhile, when Mrs Griggs encourages pupils to step out of their comfort zones and challenge themselves, Martha and Ollie set about researching the transfer of germs from various contaminated sources onto a human subject. Phobic Ollie is tested to the max, with the ultimate challenge being to kiss someone. Also, Mr Malone is freaked out because he thinks Mrs Griggs is flirting with him.