Cast Members Stephen Amell, Right, And Katie Cassidy Attend A Panel For 'Arrow.'
Cast members Stephen Amell (R) and Katie Cassidy attend a panel for "Arrow" during the CW television portion of the Television Critics Association summer press tour in Beverly Hills, California July 30, 2012. Reuters

"Arrow" Season 3, Episode 8, titled "The Brave and the Bold," airs Wednesday, Dec. 3, on The CW. This week's new episode welcomes Barry Allen aka The Flash to Starling City. This happens after Oliver Queen makes a trip to Central City to look into a villain that uses a deadly boomerang. This show concludes the year's crossover special for the fans of both DC Comics adaptations.

Spoiler alert: This preview contains Arrow Season 3 spoilers. Reports on what happens next to the Sara Lance murder case are also included.

"A crossover event that began on "The Flash" concludes with Oliver teaming with the Flash to stop a boomerang-wielding killer who plants five bombs in the city that are set to explode at the same time," reads the episode synopsis of Arrow Season 3, Episode 8, on TV.com.

In The Flash on Tuesday, Oliver Queen aka The Arrow helps Barry Allen capture Ray Bivolo, the metahuman who triggers people's rage buttons to gain control. This Wednesday, Barry returns the favour by joining Team Arrow and helping him catch a boomerang, or the villain who uses it as a murder weapon.

Avid viewers are eager to see more of the Barry Allen and Oliver Queen dynamics. Things got rough between the two in The Flash, and more conflict is expected as the two heroes find ways to work together in Arrow Season 3, Episode 8.

Meanwhile, Felicity Smoak makes good use of Team Arrow's visit to the STAR Labs in Central City by asking Caitlin for help in DNA matching. Sara Lance's killer remains unknown, but Felicity has some traces of his or her DNA.

Arrow Season 3 spoiler reports reveal that Bex Taylor-Klaus is reprising her role as Sin later in Episode 12. Sin ""plays a pivotal part in the investigation into Sara's death," show boss Andrew Kreisberg was quoted in this TV Line report.

Manu Bennett, who plays Slade Wilson aka Deathstroke, is also returning. In this MTV report, Deathstroke is showing up in Arrow Season 3, Episode 14. The report sparks suspicion that Deathstroke may have a hand in Sara's murder.